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  1. # SPDX-License-Identifier: GPL-2.0+
  2. #
  3. # (C) Copyright 2000 - 2013
  4. # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
  5. Summary:
  6. ========
  7. This directory contains the source code for U-Boot, a boot loader for
  8. Embedded boards based on PowerPC, ARM, MIPS and several other
  9. processors, which can be installed in a boot ROM and used to
  10. initialize and test the hardware or to download and run application
  11. code.
  12. The development of U-Boot is closely related to Linux: some parts of
  13. the source code originate in the Linux source tree, we have some
  14. header files in common, and special provision has been made to
  15. support booting of Linux images.
  16. Some attention has been paid to make this software easily
  17. configurable and extendable. For instance, all monitor commands are
  18. implemented with the same call interface, so that it's very easy to
  19. add new commands. Also, instead of permanently adding rarely used
  20. code (for instance hardware test utilities) to the monitor, you can
  21. load and run it dynamically.
  22. Status:
  23. =======
  24. In general, all boards for which a configuration option exists in the
  25. Makefile have been tested to some extent and can be considered
  26. "working". In fact, many of them are used in production systems.
  27. In case of problems see the CHANGELOG file to find out who contributed
  28. the specific port. In addition, there are various MAINTAINERS files
  29. scattered throughout the U-Boot source identifying the people or
  30. companies responsible for various boards and subsystems.
  31. Note: As of August, 2010, there is no longer a CHANGELOG file in the
  32. actual U-Boot source tree; however, it can be created dynamically
  33. from the Git log using:
  34. make CHANGELOG
  35. Where to get help:
  36. ==================
  37. In case you have questions about, problems with or contributions for
  38. U-Boot, you should send a message to the U-Boot mailing list at
  39. <u-boot@lists.denx.de>. There is also an archive of previous traffic
  40. on the mailing list - please search the archive before asking FAQ's.
  41. Please see https://lists.denx.de/pipermail/u-boot and
  42. https://marc.info/?l=u-boot
  43. Where to get source code:
  44. =========================
  45. The U-Boot source code is maintained in the Git repository at
  46. https://source.denx.de/u-boot/u-boot.git ; you can browse it online at
  47. https://source.denx.de/u-boot/u-boot
  48. The "Tags" links on this page allow you to download tarballs of
  49. any version you might be interested in. Official releases are also
  50. available from the DENX file server through HTTPS or FTP.
  51. https://ftp.denx.de/pub/u-boot/
  52. ftp://ftp.denx.de/pub/u-boot/
  53. Where we come from:
  54. ===================
  55. - start from 8xxrom sources
  56. - create PPCBoot project (https://sourceforge.net/projects/ppcboot)
  57. - clean up code
  58. - make it easier to add custom boards
  59. - make it possible to add other [PowerPC] CPUs
  60. - extend functions, especially:
  61. * Provide extended interface to Linux boot loader
  62. * S-Record download
  63. * network boot
  64. * ATA disk / SCSI ... boot
  65. - create ARMBoot project (https://sourceforge.net/projects/armboot)
  66. - add other CPU families (starting with ARM)
  67. - create U-Boot project (https://sourceforge.net/projects/u-boot)
  68. - current project page: see https://www.denx.de/wiki/U-Boot
  69. Names and Spelling:
  70. ===================
  71. The "official" name of this project is "Das U-Boot". The spelling
  72. "U-Boot" shall be used in all written text (documentation, comments
  73. in source files etc.). Example:
  74. This is the README file for the U-Boot project.
  75. File names etc. shall be based on the string "u-boot". Examples:
  76. include/asm-ppc/u-boot.h
  77. #include <asm/u-boot.h>
  78. Variable names, preprocessor constants etc. shall be either based on
  79. the string "u_boot" or on "U_BOOT". Example:
  80. U_BOOT_VERSION u_boot_logo
  81. IH_OS_U_BOOT u_boot_hush_start
  82. Versioning:
  83. ===========
  84. Starting with the release in October 2008, the names of the releases
  85. were changed from numerical release numbers without deeper meaning
  86. into a time stamp based numbering. Regular releases are identified by
  87. names consisting of the calendar year and month of the release date.
  88. Additional fields (if present) indicate release candidates or bug fix
  89. releases in "stable" maintenance trees.
  90. Examples:
  91. U-Boot v2009.11 - Release November 2009
  92. U-Boot v2009.11.1 - Release 1 in version November 2009 stable tree
  93. U-Boot v2010.09-rc1 - Release candidate 1 for September 2010 release
  94. Directory Hierarchy:
  95. ====================
  96. /arch Architecture-specific files
  97. /arc Files generic to ARC architecture
  98. /arm Files generic to ARM architecture
  99. /m68k Files generic to m68k architecture
  100. /microblaze Files generic to microblaze architecture
  101. /mips Files generic to MIPS architecture
  102. /nds32 Files generic to NDS32 architecture
  103. /nios2 Files generic to Altera NIOS2 architecture
  104. /powerpc Files generic to PowerPC architecture
  105. /riscv Files generic to RISC-V architecture
  106. /sandbox Files generic to HW-independent "sandbox"
  107. /sh Files generic to SH architecture
  108. /x86 Files generic to x86 architecture
  109. /xtensa Files generic to Xtensa architecture
  110. /api Machine/arch-independent API for external apps
  111. /board Board-dependent files
  112. /cmd U-Boot commands functions
  113. /common Misc architecture-independent functions
  114. /configs Board default configuration files
  115. /disk Code for disk drive partition handling
  116. /doc Documentation (a mix of ReST and READMEs)
  117. /drivers Device drivers
  118. /dts Makefile for building internal U-Boot fdt.
  119. /env Environment support
  120. /examples Example code for standalone applications, etc.
  121. /fs Filesystem code (cramfs, ext2, jffs2, etc.)
  122. /include Header Files
  123. /lib Library routines generic to all architectures
  124. /Licenses Various license files
  125. /net Networking code
  126. /post Power On Self Test
  127. /scripts Various build scripts and Makefiles
  128. /test Various unit test files
  129. /tools Tools to build and sign FIT images, etc.
  130. Software Configuration:
  131. =======================
  132. Configuration is usually done using C preprocessor defines; the
  133. rationale behind that is to avoid dead code whenever possible.
  134. There are two classes of configuration variables:
  135. * Configuration _OPTIONS_:
  136. These are selectable by the user and have names beginning with
  137. "CONFIG_".
  138. * Configuration _SETTINGS_:
  139. These depend on the hardware etc. and should not be meddled with if
  140. you don't know what you're doing; they have names beginning with
  141. "CONFIG_SYS_".
  142. Previously, all configuration was done by hand, which involved creating
  143. symbolic links and editing configuration files manually. More recently,
  144. U-Boot has added the Kbuild infrastructure used by the Linux kernel,
  145. allowing you to use the "make menuconfig" command to configure your
  146. build.
  147. Selection of Processor Architecture and Board Type:
  148. ---------------------------------------------------
  149. For all supported boards there are ready-to-use default
  150. configurations available; just type "make <board_name>_defconfig".
  151. Example: For a TQM823L module type:
  152. cd u-boot
  153. make TQM823L_defconfig
  154. Note: If you're looking for the default configuration file for a board
  155. you're sure used to be there but is now missing, check the file
  156. doc/README.scrapyard for a list of no longer supported boards.
  157. Sandbox Environment:
  158. --------------------
  159. U-Boot can be built natively to run on a Linux host using the 'sandbox'
  160. board. This allows feature development which is not board- or architecture-
  161. specific to be undertaken on a native platform. The sandbox is also used to
  162. run some of U-Boot's tests.
  163. See doc/arch/sandbox.rst for more details.
  164. Board Initialisation Flow:
  165. --------------------------
  166. This is the intended start-up flow for boards. This should apply for both
  167. SPL and U-Boot proper (i.e. they both follow the same rules).
  168. Note: "SPL" stands for "Secondary Program Loader," which is explained in
  169. more detail later in this file.
  170. At present, SPL mostly uses a separate code path, but the function names
  171. and roles of each function are the same. Some boards or architectures
  172. may not conform to this. At least most ARM boards which use
  173. CONFIG_SPL_FRAMEWORK conform to this.
  174. Execution typically starts with an architecture-specific (and possibly
  175. CPU-specific) start.S file, such as:
  176. - arch/arm/cpu/armv7/start.S
  177. - arch/powerpc/cpu/mpc83xx/start.S
  178. - arch/mips/cpu/start.S
  179. and so on. From there, three functions are called; the purpose and
  180. limitations of each of these functions are described below.
  181. lowlevel_init():
  182. - purpose: essential init to permit execution to reach board_init_f()
  183. - no global_data or BSS
  184. - there is no stack (ARMv7 may have one but it will soon be removed)
  185. - must not set up SDRAM or use console
  186. - must only do the bare minimum to allow execution to continue to
  187. board_init_f()
  188. - this is almost never needed
  189. - return normally from this function
  190. board_init_f():
  191. - purpose: set up the machine ready for running board_init_r():
  192. i.e. SDRAM and serial UART
  193. - global_data is available
  194. - stack is in SRAM
  195. - BSS is not available, so you cannot use global/static variables,
  196. only stack variables and global_data
  197. Non-SPL-specific notes:
  198. - dram_init() is called to set up DRAM. If already done in SPL this
  199. can do nothing
  200. SPL-specific notes:
  201. - you can override the entire board_init_f() function with your own
  202. version as needed.
  203. - preloader_console_init() can be called here in extremis
  204. - should set up SDRAM, and anything needed to make the UART work
  205. - there is no need to clear BSS, it will be done by crt0.S
  206. - for specific scenarios on certain architectures an early BSS *can*
  207. be made available (via CONFIG_SPL_EARLY_BSS by moving the clearing
  208. of BSS prior to entering board_init_f()) but doing so is discouraged.
  209. Instead it is strongly recommended to architect any code changes
  210. or additions such to not depend on the availability of BSS during
  211. board_init_f() as indicated in other sections of this README to
  212. maintain compatibility and consistency across the entire code base.
  213. - must return normally from this function (don't call board_init_r()
  214. directly)
  215. Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
  216. this point the stack and global_data are relocated to below
  217. CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
  218. memory.
  219. board_init_r():
  220. - purpose: main execution, common code
  221. - global_data is available
  222. - SDRAM is available
  223. - BSS is available, all static/global variables can be used
  224. - execution eventually continues to main_loop()
  225. Non-SPL-specific notes:
  226. - U-Boot is relocated to the top of memory and is now running from
  227. there.
  228. SPL-specific notes:
  229. - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
  230. CONFIG_SPL_STACK_R_ADDR points into SDRAM
  231. - preloader_console_init() can be called here - typically this is
  232. done by selecting CONFIG_SPL_BOARD_INIT and then supplying a
  233. spl_board_init() function containing this call
  234. - loads U-Boot or (in falcon mode) Linux
  235. Configuration Options:
  236. ----------------------
  237. Configuration depends on the combination of board and CPU type; all
  238. such information is kept in a configuration file
  239. "include/configs/<board_name>.h".
  240. Example: For a TQM823L module, all configuration settings are in
  241. "include/configs/TQM823L.h".
  242. Many of the options are named exactly as the corresponding Linux
  243. kernel configuration options. The intention is to make it easier to
  244. build a config tool - later.
  245. - ARM Platform Bus Type(CCI):
  246. CoreLink Cache Coherent Interconnect (CCI) is ARM BUS which
  247. provides full cache coherency between two clusters of multi-core
  248. CPUs and I/O coherency for devices and I/O masters
  249. CONFIG_SYS_FSL_HAS_CCI400
  250. Defined For SoC that has cache coherent interconnect
  251. CCN-400
  252. CONFIG_SYS_FSL_HAS_CCN504
  253. Defined for SoC that has cache coherent interconnect CCN-504
  254. The following options need to be configured:
  255. - CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
  256. - Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
  257. - 85xx CPU Options:
  258. CONFIG_SYS_PPC64
  259. Specifies that the core is a 64-bit PowerPC implementation (implements
  260. the "64" category of the Power ISA). This is necessary for ePAPR
  261. compliance, among other possible reasons.
  262. CONFIG_SYS_FSL_TBCLK_DIV
  263. Defines the core time base clock divider ratio compared to the
  264. system clock. On most PQ3 devices this is 8, on newer QorIQ
  265. devices it can be 16 or 32. The ratio varies from SoC to Soc.
  266. CONFIG_SYS_FSL_PCIE_COMPAT
  267. Defines the string to utilize when trying to match PCIe device
  268. tree nodes for the given platform.
  269. CONFIG_SYS_FSL_ERRATUM_A004510
  270. Enables a workaround for erratum A004510. If set,
  271. then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
  272. CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
  273. CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
  274. CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
  275. Defines one or two SoC revisions (low 8 bits of SVR)
  276. for which the A004510 workaround should be applied.
  277. The rest of SVR is either not relevant to the decision
  278. of whether the erratum is present (e.g. p2040 versus
  279. p2041) or is implied by the build target, which controls
  280. whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
  281. See Freescale App Note 4493 for more information about
  282. this erratum.
  283. CONFIG_A003399_NOR_WORKAROUND
  284. Enables a workaround for IFC erratum A003399. It is only
  285. required during NOR boot.
  286. CONFIG_A008044_WORKAROUND
  287. Enables a workaround for T1040/T1042 erratum A008044. It is only
  288. required during NAND boot and valid for Rev 1.0 SoC revision
  289. CONFIG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
  290. This is the value to write into CCSR offset 0x18600
  291. according to the A004510 workaround.
  292. CONFIG_SYS_FSL_DSP_DDR_ADDR
  293. This value denotes start offset of DDR memory which is
  294. connected exclusively to the DSP cores.
  295. CONFIG_SYS_FSL_DSP_M2_RAM_ADDR
  296. This value denotes start offset of M2 memory
  297. which is directly connected to the DSP core.
  298. CONFIG_SYS_FSL_DSP_M3_RAM_ADDR
  299. This value denotes start offset of M3 memory which is directly
  300. connected to the DSP core.
  301. CONFIG_SYS_FSL_DSP_CCSRBAR_DEFAULT
  302. This value denotes start offset of DSP CCSR space.
  303. CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
  304. Single Source Clock is clocking mode present in some of FSL SoC's.
  305. In this mode, a single differential clock is used to supply
  306. clocks to the sysclock, ddrclock and usbclock.
  307. CONFIG_SYS_CPC_REINIT_F
  308. This CONFIG is defined when the CPC is configured as SRAM at the
  309. time of U-Boot entry and is required to be re-initialized.
  310. CONFIG_DEEP_SLEEP
  311. Indicates this SoC supports deep sleep feature. If deep sleep is
  312. supported, core will start to execute uboot when wakes up.
  313. - Generic CPU options:
  314. CONFIG_SYS_BIG_ENDIAN, CONFIG_SYS_LITTLE_ENDIAN
  315. Defines the endianess of the CPU. Implementation of those
  316. values is arch specific.
  317. CONFIG_SYS_FSL_DDR
  318. Freescale DDR driver in use. This type of DDR controller is
  319. found in mpc83xx, mpc85xx as well as some ARM core SoCs.
  320. CONFIG_SYS_FSL_DDR_ADDR
  321. Freescale DDR memory-mapped register base.
  322. CONFIG_SYS_FSL_DDR_EMU
  323. Specify emulator support for DDR. Some DDR features such as
  324. deskew training are not available.
  325. CONFIG_SYS_FSL_DDRC_GEN1
  326. Freescale DDR1 controller.
  327. CONFIG_SYS_FSL_DDRC_GEN2
  328. Freescale DDR2 controller.
  329. CONFIG_SYS_FSL_DDRC_GEN3
  330. Freescale DDR3 controller.
  331. CONFIG_SYS_FSL_DDRC_GEN4
  332. Freescale DDR4 controller.
  333. CONFIG_SYS_FSL_DDRC_ARM_GEN3
  334. Freescale DDR3 controller for ARM-based SoCs.
  335. CONFIG_SYS_FSL_DDR1
  336. Board config to use DDR1. It can be enabled for SoCs with
  337. Freescale DDR1 or DDR2 controllers, depending on the board
  338. implemetation.
  339. CONFIG_SYS_FSL_DDR2
  340. Board config to use DDR2. It can be enabled for SoCs with
  341. Freescale DDR2 or DDR3 controllers, depending on the board
  342. implementation.
  343. CONFIG_SYS_FSL_DDR3
  344. Board config to use DDR3. It can be enabled for SoCs with
  345. Freescale DDR3 or DDR3L controllers.
  346. CONFIG_SYS_FSL_DDR3L
  347. Board config to use DDR3L. It can be enabled for SoCs with
  348. DDR3L controllers.
  349. CONFIG_SYS_FSL_IFC_BE
  350. Defines the IFC controller register space as Big Endian
  351. CONFIG_SYS_FSL_IFC_LE
  352. Defines the IFC controller register space as Little Endian
  353. CONFIG_SYS_FSL_IFC_CLK_DIV
  354. Defines divider of platform clock(clock input to IFC controller).
  355. CONFIG_SYS_FSL_LBC_CLK_DIV
  356. Defines divider of platform clock(clock input to eLBC controller).
  357. CONFIG_SYS_FSL_DDR_BE
  358. Defines the DDR controller register space as Big Endian
  359. CONFIG_SYS_FSL_DDR_LE
  360. Defines the DDR controller register space as Little Endian
  361. CONFIG_SYS_FSL_DDR_SDRAM_BASE_PHY
  362. Physical address from the view of DDR controllers. It is the
  363. same as CONFIG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
  364. it could be different for ARM SoCs.
  365. CONFIG_SYS_FSL_DDR_INTLV_256B
  366. DDR controller interleaving on 256-byte. This is a special
  367. interleaving mode, handled by Dickens for Freescale layerscape
  368. SoCs with ARM core.
  369. CONFIG_SYS_FSL_DDR_MAIN_NUM_CTRLS
  370. Number of controllers used as main memory.
  371. CONFIG_SYS_FSL_OTHER_DDR_NUM_CTRLS
  372. Number of controllers used for other than main memory.
  373. CONFIG_SYS_FSL_HAS_DP_DDR
  374. Defines the SoC has DP-DDR used for DPAA.
  375. CONFIG_SYS_FSL_SEC_BE
  376. Defines the SEC controller register space as Big Endian
  377. CONFIG_SYS_FSL_SEC_LE
  378. Defines the SEC controller register space as Little Endian
  379. - MIPS CPU options:
  380. CONFIG_SYS_INIT_SP_OFFSET
  381. Offset relative to CONFIG_SYS_SDRAM_BASE for initial stack
  382. pointer. This is needed for the temporary stack before
  383. relocation.
  384. CONFIG_XWAY_SWAP_BYTES
  385. Enable compilation of tools/xway-swap-bytes needed for Lantiq
  386. XWAY SoCs for booting from NOR flash. The U-Boot image needs to
  387. be swapped if a flash programmer is used.
  388. - ARM options:
  389. CONFIG_SYS_EXCEPTION_VECTORS_HIGH
  390. Select high exception vectors of the ARM core, e.g., do not
  391. clear the V bit of the c1 register of CP15.
  392. COUNTER_FREQUENCY
  393. Generic timer clock source frequency.
  394. COUNTER_FREQUENCY_REAL
  395. Generic timer clock source frequency if the real clock is
  396. different from COUNTER_FREQUENCY, and can only be determined
  397. at run time.
  398. - Tegra SoC options:
  399. CONFIG_TEGRA_SUPPORT_NON_SECURE
  400. Support executing U-Boot in non-secure (NS) mode. Certain
  401. impossible actions will be skipped if the CPU is in NS mode,
  402. such as ARM architectural timer initialization.
  403. - Linux Kernel Interface:
  404. CONFIG_MEMSIZE_IN_BYTES [relevant for MIPS only]
  405. When transferring memsize parameter to Linux, some versions
  406. expect it to be in bytes, others in MB.
  407. Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.
  408. CONFIG_OF_LIBFDT
  409. New kernel versions are expecting firmware settings to be
  410. passed using flattened device trees (based on open firmware
  411. concepts).
  412. CONFIG_OF_LIBFDT
  413. * New libfdt-based support
  414. * Adds the "fdt" command
  415. * The bootm command automatically updates the fdt
  416. OF_TBCLK - The timebase frequency.
  417. boards with QUICC Engines require OF_QE to set UCC MAC
  418. addresses
  419. CONFIG_OF_BOARD_SETUP
  420. Board code has addition modification that it wants to make
  421. to the flat device tree before handing it off to the kernel
  422. CONFIG_OF_SYSTEM_SETUP
  423. Other code has addition modification that it wants to make
  424. to the flat device tree before handing it off to the kernel.
  425. This causes ft_system_setup() to be called before booting
  426. the kernel.
  427. CONFIG_OF_IDE_FIXUP
  428. U-Boot can detect if an IDE device is present or not.
  429. If not, and this new config option is activated, U-Boot
  430. removes the ATA node from the DTS before booting Linux,
  431. so the Linux IDE driver does not probe the device and
  432. crash. This is needed for buggy hardware (uc101) where
  433. no pull down resistor is connected to the signal IDE5V_DD7.
  434. - vxWorks boot parameters:
  435. bootvx constructs a valid bootline using the following
  436. environments variables: bootdev, bootfile, ipaddr, netmask,
  437. serverip, gatewayip, hostname, othbootargs.
  438. It loads the vxWorks image pointed bootfile.
  439. Note: If a "bootargs" environment is defined, it will override
  440. the defaults discussed just above.
  441. - Cache Configuration:
  442. CONFIG_SYS_L2CACHE_OFF- Do not enable L2 cache in U-Boot
  443. - Cache Configuration for ARM:
  444. CONFIG_SYS_L2_PL310 - Enable support for ARM PL310 L2 cache
  445. controller
  446. CONFIG_SYS_PL310_BASE - Physical base address of PL310
  447. controller register space
  448. - Serial Ports:
  449. CONFIG_PL011_SERIAL
  450. Define this if you want support for Amba PrimeCell PL011 UARTs.
  451. CONFIG_PL011_CLOCK
  452. If you have Amba PrimeCell PL011 UARTs, set this variable to
  453. the clock speed of the UARTs.
  454. CONFIG_PL01x_PORTS
  455. If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
  456. define this to a list of base addresses for each (supported)
  457. port. See e.g. include/configs/versatile.h
  458. CONFIG_SERIAL_HW_FLOW_CONTROL
  459. Define this variable to enable hw flow control in serial driver.
  460. Current user of this option is drivers/serial/nsl16550.c driver
  461. - Autoboot Command:
  462. CONFIG_BOOTCOMMAND
  463. Only needed when CONFIG_BOOTDELAY is enabled;
  464. define a command string that is automatically executed
  465. when no character is read on the console interface
  466. within "Boot Delay" after reset.
  467. CONFIG_RAMBOOT and CONFIG_NFSBOOT
  468. The value of these goes into the environment as
  469. "ramboot" and "nfsboot" respectively, and can be used
  470. as a convenience, when switching between booting from
  471. RAM and NFS.
  472. - Serial Download Echo Mode:
  473. CONFIG_LOADS_ECHO
  474. If defined to 1, all characters received during a
  475. serial download (using the "loads" command) are
  476. echoed back. This might be needed by some terminal
  477. emulations (like "cu"), but may as well just take
  478. time on others. This setting #define's the initial
  479. value of the "loads_echo" environment variable.
  480. - Removal of commands
  481. If no commands are needed to boot, you can disable
  482. CONFIG_CMDLINE to remove them. In this case, the command line
  483. will not be available, and when U-Boot wants to execute the
  484. boot command (on start-up) it will call board_run_command()
  485. instead. This can reduce image size significantly for very
  486. simple boot procedures.
  487. - Regular expression support:
  488. CONFIG_REGEX
  489. If this variable is defined, U-Boot is linked against
  490. the SLRE (Super Light Regular Expression) library,
  491. which adds regex support to some commands, as for
  492. example "env grep" and "setexpr".
  493. - Device tree:
  494. CONFIG_OF_CONTROL
  495. If this variable is defined, U-Boot will use a device tree
  496. to configure its devices, instead of relying on statically
  497. compiled #defines in the board file. This option is
  498. experimental and only available on a few boards. The device
  499. tree is available in the global data as gd->fdt_blob.
  500. U-Boot needs to get its device tree from somewhere. This can
  501. be done using one of the three options below:
  502. CONFIG_OF_EMBED
  503. If this variable is defined, U-Boot will embed a device tree
  504. binary in its image. This device tree file should be in the
  505. board directory and called <soc>-<board>.dts. The binary file
  506. is then picked up in board_init_f() and made available through
  507. the global data structure as gd->fdt_blob.
  508. CONFIG_OF_SEPARATE
  509. If this variable is defined, U-Boot will build a device tree
  510. binary. It will be called u-boot.dtb. Architecture-specific
  511. code will locate it at run-time. Generally this works by:
  512. cat u-boot.bin u-boot.dtb >image.bin
  513. and in fact, U-Boot does this for you, creating a file called
  514. u-boot-dtb.bin which is useful in the common case. You can
  515. still use the individual files if you need something more
  516. exotic.
  517. CONFIG_OF_BOARD
  518. If this variable is defined, U-Boot will use the device tree
  519. provided by the board at runtime instead of embedding one with
  520. the image. Only boards defining board_fdt_blob_setup() support
  521. this option (see include/fdtdec.h file).
  522. - Watchdog:
  523. CONFIG_WATCHDOG
  524. If this variable is defined, it enables watchdog
  525. support for the SoC. There must be support in the SoC
  526. specific code for a watchdog. For the 8xx
  527. CPUs, the SIU Watchdog feature is enabled in the SYPCR
  528. register. When supported for a specific SoC is
  529. available, then no further board specific code should
  530. be needed to use it.
  531. CONFIG_HW_WATCHDOG
  532. When using a watchdog circuitry external to the used
  533. SoC, then define this variable and provide board
  534. specific code for the "hw_watchdog_reset" function.
  535. CONFIG_SYS_WATCHDOG_FREQ
  536. Some platforms automatically call WATCHDOG_RESET()
  537. from the timer interrupt handler every
  538. CONFIG_SYS_WATCHDOG_FREQ interrupts. If not set by the
  539. board configuration file, a default of CONFIG_SYS_HZ/2
  540. (i.e. 500) is used. Setting CONFIG_SYS_WATCHDOG_FREQ
  541. to 0 disables calling WATCHDOG_RESET() from the timer
  542. interrupt.
  543. - Real-Time Clock:
  544. When CONFIG_CMD_DATE is selected, the type of the RTC
  545. has to be selected, too. Define exactly one of the
  546. following options:
  547. CONFIG_RTC_PCF8563 - use Philips PCF8563 RTC
  548. CONFIG_RTC_MC13XXX - use MC13783 or MC13892 RTC
  549. CONFIG_RTC_MC146818 - use MC146818 RTC
  550. CONFIG_RTC_DS1307 - use Maxim, Inc. DS1307 RTC
  551. CONFIG_RTC_DS1337 - use Maxim, Inc. DS1337 RTC
  552. CONFIG_RTC_DS1338 - use Maxim, Inc. DS1338 RTC
  553. CONFIG_RTC_DS1339 - use Maxim, Inc. DS1339 RTC
  554. CONFIG_RTC_DS164x - use Dallas DS164x RTC
  555. CONFIG_RTC_ISL1208 - use Intersil ISL1208 RTC
  556. CONFIG_RTC_MAX6900 - use Maxim, Inc. MAX6900 RTC
  557. CONFIG_RTC_DS1337_NOOSC - Turn off the OSC output for DS1337
  558. CONFIG_SYS_RV3029_TCR - enable trickle charger on
  559. RV3029 RTC.
  560. Note that if the RTC uses I2C, then the I2C interface
  561. must also be configured. See I2C Support, below.
  562. - GPIO Support:
  563. CONFIG_PCA953X - use NXP's PCA953X series I2C GPIO
  564. The CONFIG_SYS_I2C_PCA953X_WIDTH option specifies a list of
  565. chip-ngpio pairs that tell the PCA953X driver the number of
  566. pins supported by a particular chip.
  567. Note that if the GPIO device uses I2C, then the I2C interface
  568. must also be configured. See I2C Support, below.
  569. - I/O tracing:
  570. When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
  571. accesses and can checksum them or write a list of them out
  572. to memory. See the 'iotrace' command for details. This is
  573. useful for testing device drivers since it can confirm that
  574. the driver behaves the same way before and after a code
  575. change. Currently this is supported on sandbox and arm. To
  576. add support for your architecture, add '#include <iotrace.h>'
  577. to the bottom of arch/<arch>/include/asm/io.h and test.
  578. Example output from the 'iotrace stats' command is below.
  579. Note that if the trace buffer is exhausted, the checksum will
  580. still continue to operate.
  581. iotrace is enabled
  582. Start: 10000000 (buffer start address)
  583. Size: 00010000 (buffer size)
  584. Offset: 00000120 (current buffer offset)
  585. Output: 10000120 (start + offset)
  586. Count: 00000018 (number of trace records)
  587. CRC32: 9526fb66 (CRC32 of all trace records)
  588. - Timestamp Support:
  589. When CONFIG_TIMESTAMP is selected, the timestamp
  590. (date and time) of an image is printed by image
  591. commands like bootm or iminfo. This option is
  592. automatically enabled when you select CONFIG_CMD_DATE .
  593. - Partition Labels (disklabels) Supported:
  594. Zero or more of the following:
  595. CONFIG_MAC_PARTITION Apple's MacOS partition table.
  596. CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
  597. CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
  598. bootloader. Note 2TB partition limit; see
  599. disk/part_efi.c
  600. CONFIG_SCSI) you must configure support for at
  601. least one non-MTD partition type as well.
  602. - IDE Reset method:
  603. CONFIG_IDE_RESET_ROUTINE - this is defined in several
  604. board configurations files but used nowhere!
  605. CONFIG_IDE_RESET - is this is defined, IDE Reset will
  606. be performed by calling the function
  607. ide_set_reset(int reset)
  608. which has to be defined in a board specific file
  609. - ATAPI Support:
  610. CONFIG_ATAPI
  611. Set this to enable ATAPI support.
  612. - LBA48 Support
  613. CONFIG_LBA48
  614. Set this to enable support for disks larger than 137GB
  615. Also look at CONFIG_SYS_64BIT_LBA.
  616. Whithout these , LBA48 support uses 32bit variables and will 'only'
  617. support disks up to 2.1TB.
  618. CONFIG_SYS_64BIT_LBA:
  619. When enabled, makes the IDE subsystem use 64bit sector addresses.
  620. Default is 32bit.
  621. - SCSI Support:
  622. CONFIG_SYS_SCSI_MAX_LUN [8], CONFIG_SYS_SCSI_MAX_SCSI_ID [7] and
  623. CONFIG_SYS_SCSI_MAX_DEVICE [CONFIG_SYS_SCSI_MAX_SCSI_ID *
  624. CONFIG_SYS_SCSI_MAX_LUN] can be adjusted to define the
  625. maximum numbers of LUNs, SCSI ID's and target
  626. devices.
  627. The environment variable 'scsidevs' is set to the number of
  628. SCSI devices found during the last scan.
  629. - NETWORK Support (PCI):
  630. CONFIG_E1000
  631. Support for Intel 8254x/8257x gigabit chips.
  632. CONFIG_E1000_SPI
  633. Utility code for direct access to the SPI bus on Intel 8257x.
  634. This does not do anything useful unless you set at least one
  635. of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
  636. CONFIG_E1000_SPI_GENERIC
  637. Allow generic access to the SPI bus on the Intel 8257x, for
  638. example with the "sspi" command.
  639. CONFIG_NATSEMI
  640. Support for National dp83815 chips.
  641. CONFIG_NS8382X
  642. Support for National dp8382[01] gigabit chips.
  643. - NETWORK Support (other):
  644. CONFIG_CALXEDA_XGMAC
  645. Support for the Calxeda XGMAC device
  646. CONFIG_LAN91C96
  647. Support for SMSC's LAN91C96 chips.
  648. CONFIG_LAN91C96_USE_32_BIT
  649. Define this to enable 32 bit addressing
  650. CONFIG_SMC91111
  651. Support for SMSC's LAN91C111 chip
  652. CONFIG_SMC91111_BASE
  653. Define this to hold the physical address
  654. of the device (I/O space)
  655. CONFIG_SMC_USE_32_BIT
  656. Define this if data bus is 32 bits
  657. CONFIG_SMC_USE_IOFUNCS
  658. Define this to use i/o functions instead of macros
  659. (some hardware wont work with macros)
  660. CONFIG_SYS_DAVINCI_EMAC_PHY_COUNT
  661. Define this if you have more then 3 PHYs.
  662. CONFIG_FTGMAC100
  663. Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
  664. CONFIG_FTGMAC100_EGIGA
  665. Define this to use GE link update with gigabit PHY.
  666. Define this if FTGMAC100 is connected to gigabit PHY.
  667. If your system has 10/100 PHY only, it might not occur
  668. wrong behavior. Because PHY usually return timeout or
  669. useless data when polling gigabit status and gigabit
  670. control registers. This behavior won't affect the
  671. correctnessof 10/100 link speed update.
  672. CONFIG_SH_ETHER
  673. Support for Renesas on-chip Ethernet controller
  674. CONFIG_SH_ETHER_USE_PORT
  675. Define the number of ports to be used
  676. CONFIG_SH_ETHER_PHY_ADDR
  677. Define the ETH PHY's address
  678. CONFIG_SH_ETHER_CACHE_WRITEBACK
  679. If this option is set, the driver enables cache flush.
  680. - TPM Support:
  681. CONFIG_TPM
  682. Support TPM devices.
  683. CONFIG_TPM_TIS_INFINEON
  684. Support for Infineon i2c bus TPM devices. Only one device
  685. per system is supported at this time.
  686. CONFIG_TPM_TIS_I2C_BURST_LIMITATION
  687. Define the burst count bytes upper limit
  688. CONFIG_TPM_ST33ZP24
  689. Support for STMicroelectronics TPM devices. Requires DM_TPM support.
  690. CONFIG_TPM_ST33ZP24_I2C
  691. Support for STMicroelectronics ST33ZP24 I2C devices.
  692. Requires TPM_ST33ZP24 and I2C.
  693. CONFIG_TPM_ST33ZP24_SPI
  694. Support for STMicroelectronics ST33ZP24 SPI devices.
  695. Requires TPM_ST33ZP24 and SPI.
  696. CONFIG_TPM_ATMEL_TWI
  697. Support for Atmel TWI TPM device. Requires I2C support.
  698. CONFIG_TPM_TIS_LPC
  699. Support for generic parallel port TPM devices. Only one device
  700. per system is supported at this time.
  701. CONFIG_TPM_TIS_BASE_ADDRESS
  702. Base address where the generic TPM device is mapped
  703. to. Contemporary x86 systems usually map it at
  704. 0xfed40000.
  705. CONFIG_TPM
  706. Define this to enable the TPM support library which provides
  707. functional interfaces to some TPM commands.
  708. Requires support for a TPM device.
  709. CONFIG_TPM_AUTH_SESSIONS
  710. Define this to enable authorized functions in the TPM library.
  711. Requires CONFIG_TPM and CONFIG_SHA1.
  712. - USB Support:
  713. At the moment only the UHCI host controller is
  714. supported (PIP405, MIP405); define
  715. CONFIG_USB_UHCI to enable it.
  716. define CONFIG_USB_KEYBOARD to enable the USB Keyboard
  717. and define CONFIG_USB_STORAGE to enable the USB
  718. storage devices.
  719. Note:
  720. Supported are USB Keyboards and USB Floppy drives
  721. (TEAC FD-05PUB).
  722. CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
  723. txfilltuning field in the EHCI controller on reset.
  724. CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
  725. HW module registers.
  726. - USB Device:
  727. Define the below if you wish to use the USB console.
  728. Once firmware is rebuilt from a serial console issue the
  729. command "setenv stdin usbtty; setenv stdout usbtty" and
  730. attach your USB cable. The Unix command "dmesg" should print
  731. it has found a new device. The environment variable usbtty
  732. can be set to gserial or cdc_acm to enable your device to
  733. appear to a USB host as a Linux gserial device or a
  734. Common Device Class Abstract Control Model serial device.
  735. If you select usbtty = gserial you should be able to enumerate
  736. a Linux host by
  737. # modprobe usbserial vendor=0xVendorID product=0xProductID
  738. else if using cdc_acm, simply setting the environment
  739. variable usbtty to be cdc_acm should suffice. The following
  740. might be defined in YourBoardName.h
  741. CONFIG_USB_DEVICE
  742. Define this to build a UDC device
  743. CONFIG_USB_TTY
  744. Define this to have a tty type of device available to
  745. talk to the UDC device
  746. CONFIG_USBD_HS
  747. Define this to enable the high speed support for usb
  748. device and usbtty. If this feature is enabled, a routine
  749. int is_usbd_high_speed(void)
  750. also needs to be defined by the driver to dynamically poll
  751. whether the enumeration has succeded at high speed or full
  752. speed.
  753. CONFIG_SYS_CONSOLE_IS_IN_ENV
  754. Define this if you want stdin, stdout &/or stderr to
  755. be set to usbtty.
  756. If you have a USB-IF assigned VendorID then you may wish to
  757. define your own vendor specific values either in BoardName.h
  758. or directly in usbd_vendor_info.h. If you don't define
  759. CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
  760. CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
  761. should pretend to be a Linux device to it's target host.
  762. CONFIG_USBD_MANUFACTURER
  763. Define this string as the name of your company for
  764. - CONFIG_USBD_MANUFACTURER "my company"
  765. CONFIG_USBD_PRODUCT_NAME
  766. Define this string as the name of your product
  767. - CONFIG_USBD_PRODUCT_NAME "acme usb device"
  768. CONFIG_USBD_VENDORID
  769. Define this as your assigned Vendor ID from the USB
  770. Implementors Forum. This *must* be a genuine Vendor ID
  771. to avoid polluting the USB namespace.
  772. - CONFIG_USBD_VENDORID 0xFFFF
  773. CONFIG_USBD_PRODUCTID
  774. Define this as the unique Product ID
  775. for your device
  776. - CONFIG_USBD_PRODUCTID 0xFFFF
  777. - ULPI Layer Support:
  778. The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
  779. the generic ULPI layer. The generic layer accesses the ULPI PHY
  780. via the platform viewport, so you need both the genric layer and
  781. the viewport enabled. Currently only Chipidea/ARC based
  782. viewport is supported.
  783. To enable the ULPI layer support, define CONFIG_USB_ULPI and
  784. CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
  785. If your ULPI phy needs a different reference clock than the
  786. standard 24 MHz then you have to define CONFIG_ULPI_REF_CLK to
  787. the appropriate value in Hz.
  788. - MMC Support:
  789. The MMC controller on the Intel PXA is supported. To
  790. enable this define CONFIG_MMC. The MMC can be
  791. accessed from the boot prompt by mapping the device
  792. to physical memory similar to flash. Command line is
  793. enabled with CONFIG_CMD_MMC. The MMC driver also works with
  794. the FAT fs. This is enabled with CONFIG_CMD_FAT.
  795. CONFIG_SH_MMCIF
  796. Support for Renesas on-chip MMCIF controller
  797. CONFIG_SH_MMCIF_ADDR
  798. Define the base address of MMCIF registers
  799. CONFIG_SH_MMCIF_CLK
  800. Define the clock frequency for MMCIF
  801. - USB Device Firmware Update (DFU) class support:
  802. CONFIG_DFU_OVER_USB
  803. This enables the USB portion of the DFU USB class
  804. CONFIG_DFU_NAND
  805. This enables support for exposing NAND devices via DFU.
  806. CONFIG_DFU_RAM
  807. This enables support for exposing RAM via DFU.
  808. Note: DFU spec refer to non-volatile memory usage, but
  809. allow usages beyond the scope of spec - here RAM usage,
  810. one that would help mostly the developer.
  811. CONFIG_SYS_DFU_DATA_BUF_SIZE
  812. Dfu transfer uses a buffer before writing data to the
  813. raw storage device. Make the size (in bytes) of this buffer
  814. configurable. The size of this buffer is also configurable
  815. through the "dfu_bufsiz" environment variable.
  816. CONFIG_SYS_DFU_MAX_FILE_SIZE
  817. When updating files rather than the raw storage device,
  818. we use a static buffer to copy the file into and then write
  819. the buffer once we've been given the whole file. Define
  820. this to the maximum filesize (in bytes) for the buffer.
  821. Default is 4 MiB if undefined.
  822. DFU_DEFAULT_POLL_TIMEOUT
  823. Poll timeout [ms], is the timeout a device can send to the
  824. host. The host must wait for this timeout before sending
  825. a subsequent DFU_GET_STATUS request to the device.
  826. DFU_MANIFEST_POLL_TIMEOUT
  827. Poll timeout [ms], which the device sends to the host when
  828. entering dfuMANIFEST state. Host waits this timeout, before
  829. sending again an USB request to the device.
  830. - Journaling Flash filesystem support:
  831. CONFIG_JFFS2_NAND
  832. Define these for a default partition on a NAND device
  833. CONFIG_SYS_JFFS2_FIRST_SECTOR,
  834. CONFIG_SYS_JFFS2_FIRST_BANK, CONFIG_SYS_JFFS2_NUM_BANKS
  835. Define these for a default partition on a NOR device
  836. - Keyboard Support:
  837. See Kconfig help for available keyboard drivers.
  838. CONFIG_KEYBOARD
  839. Define this to enable a custom keyboard support.
  840. This simply calls drv_keyboard_init() which must be
  841. defined in your board-specific files. This option is deprecated
  842. and is only used by novena. For new boards, use driver model
  843. instead.
  844. - Video support:
  845. CONFIG_FSL_DIU_FB
  846. Enable the Freescale DIU video driver. Reference boards for
  847. SOCs that have a DIU should define this macro to enable DIU
  848. support, and should also define these other macros:
  849. CONFIG_SYS_DIU_ADDR
  850. CONFIG_VIDEO
  851. CONFIG_CFB_CONSOLE
  852. CONFIG_VIDEO_SW_CURSOR
  853. CONFIG_VGA_AS_SINGLE_DEVICE
  854. CONFIG_VIDEO_LOGO
  855. CONFIG_VIDEO_BMP_LOGO
  856. The DIU driver will look for the 'video-mode' environment
  857. variable, and if defined, enable the DIU as a console during
  858. boot. See the documentation file doc/README.video for a
  859. description of this variable.
  860. - LCD Support: CONFIG_LCD
  861. Define this to enable LCD support (for output to LCD
  862. display); also select one of the supported displays
  863. by defining one of these:
  864. CONFIG_ATMEL_LCD:
  865. HITACHI TX09D70VM1CCA, 3.5", 240x320.
  866. CONFIG_NEC_NL6448AC33:
  867. NEC NL6448AC33-18. Active, color, single scan.
  868. CONFIG_NEC_NL6448BC20
  869. NEC NL6448BC20-08. 6.5", 640x480.
  870. Active, color, single scan.
  871. CONFIG_NEC_NL6448BC33_54
  872. NEC NL6448BC33-54. 10.4", 640x480.
  873. Active, color, single scan.
  874. CONFIG_SHARP_16x9
  875. Sharp 320x240. Active, color, single scan.
  876. It isn't 16x9, and I am not sure what it is.
  877. CONFIG_SHARP_LQ64D341
  878. Sharp LQ64D341 display, 640x480.
  879. Active, color, single scan.
  880. CONFIG_HLD1045
  881. HLD1045 display, 640x480.
  882. Active, color, single scan.
  883. CONFIG_OPTREX_BW
  884. Optrex CBL50840-2 NF-FW 99 22 M5
  885. or
  886. Hitachi LMG6912RPFC-00T
  887. or
  888. Hitachi SP14Q002
  889. 320x240. Black & white.
  890. CONFIG_LCD_ALIGNMENT
  891. Normally the LCD is page-aligned (typically 4KB). If this is
  892. defined then the LCD will be aligned to this value instead.
  893. For ARM it is sometimes useful to use MMU_SECTION_SIZE
  894. here, since it is cheaper to change data cache settings on
  895. a per-section basis.
  896. CONFIG_LCD_ROTATION
  897. Sometimes, for example if the display is mounted in portrait
  898. mode or even if it's mounted landscape but rotated by 180degree,
  899. we need to rotate our content of the display relative to the
  900. framebuffer, so that user can read the messages which are
  901. printed out.
  902. Once CONFIG_LCD_ROTATION is defined, the lcd_console will be
  903. initialized with a given rotation from "vl_rot" out of
  904. "vidinfo_t" which is provided by the board specific code.
  905. The value for vl_rot is coded as following (matching to
  906. fbcon=rotate:<n> linux-kernel commandline):
  907. 0 = no rotation respectively 0 degree
  908. 1 = 90 degree rotation
  909. 2 = 180 degree rotation
  910. 3 = 270 degree rotation
  911. If CONFIG_LCD_ROTATION is not defined, the console will be
  912. initialized with 0degree rotation.
  913. CONFIG_LCD_BMP_RLE8
  914. Support drawing of RLE8-compressed bitmaps on the LCD.
  915. CONFIG_I2C_EDID
  916. Enables an 'i2c edid' command which can read EDID
  917. information over I2C from an attached LCD display.
  918. - MII/PHY support:
  919. CONFIG_PHY_CLOCK_FREQ (ppc4xx)
  920. The clock frequency of the MII bus
  921. CONFIG_PHY_RESET_DELAY
  922. Some PHY like Intel LXT971A need extra delay after
  923. reset before any MII register access is possible.
  924. For such PHY, set this option to the usec delay
  925. required. (minimum 300usec for LXT971A)
  926. CONFIG_PHY_CMD_DELAY (ppc4xx)
  927. Some PHY like Intel LXT971A need extra delay after
  928. command issued before MII status register can be read
  929. - IP address:
  930. CONFIG_IPADDR
  931. Define a default value for the IP address to use for
  932. the default Ethernet interface, in case this is not
  933. determined through e.g. bootp.
  934. (Environment variable "ipaddr")
  935. - Server IP address:
  936. CONFIG_SERVERIP
  937. Defines a default value for the IP address of a TFTP
  938. server to contact when using the "tftboot" command.
  939. (Environment variable "serverip")
  940. CONFIG_KEEP_SERVERADDR
  941. Keeps the server's MAC address, in the env 'serveraddr'
  942. for passing to bootargs (like Linux's netconsole option)
  943. - Gateway IP address:
  944. CONFIG_GATEWAYIP
  945. Defines a default value for the IP address of the
  946. default router where packets to other networks are
  947. sent to.
  948. (Environment variable "gatewayip")
  949. - Subnet mask:
  950. CONFIG_NETMASK
  951. Defines a default value for the subnet mask (or
  952. routing prefix) which is used to determine if an IP
  953. address belongs to the local subnet or needs to be
  954. forwarded through a router.
  955. (Environment variable "netmask")
  956. - BOOTP Recovery Mode:
  957. CONFIG_BOOTP_RANDOM_DELAY
  958. If you have many targets in a network that try to
  959. boot using BOOTP, you may want to avoid that all
  960. systems send out BOOTP requests at precisely the same
  961. moment (which would happen for instance at recovery
  962. from a power failure, when all systems will try to
  963. boot, thus flooding the BOOTP server. Defining
  964. CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
  965. inserted before sending out BOOTP requests. The
  966. following delays are inserted then:
  967. 1st BOOTP request: delay 0 ... 1 sec
  968. 2nd BOOTP request: delay 0 ... 2 sec
  969. 3rd BOOTP request: delay 0 ... 4 sec
  970. 4th and following
  971. BOOTP requests: delay 0 ... 8 sec
  972. CONFIG_BOOTP_ID_CACHE_SIZE
  973. BOOTP packets are uniquely identified using a 32-bit ID. The
  974. server will copy the ID from client requests to responses and
  975. U-Boot will use this to determine if it is the destination of
  976. an incoming response. Some servers will check that addresses
  977. aren't in use before handing them out (usually using an ARP
  978. ping) and therefore take up to a few hundred milliseconds to
  979. respond. Network congestion may also influence the time it
  980. takes for a response to make it back to the client. If that
  981. time is too long, U-Boot will retransmit requests. In order
  982. to allow earlier responses to still be accepted after these
  983. retransmissions, U-Boot's BOOTP client keeps a small cache of
  984. IDs. The CONFIG_BOOTP_ID_CACHE_SIZE controls the size of this
  985. cache. The default is to keep IDs for up to four outstanding
  986. requests. Increasing this will allow U-Boot to accept offers
  987. from a BOOTP client in networks with unusually high latency.
  988. - DHCP Advanced Options:
  989. You can fine tune the DHCP functionality by defining
  990. CONFIG_BOOTP_* symbols:
  991. CONFIG_BOOTP_NISDOMAIN
  992. CONFIG_BOOTP_BOOTFILESIZE
  993. CONFIG_BOOTP_NTPSERVER
  994. CONFIG_BOOTP_TIMEOFFSET
  995. CONFIG_BOOTP_VENDOREX
  996. CONFIG_BOOTP_MAY_FAIL
  997. CONFIG_BOOTP_SERVERIP - TFTP server will be the serverip
  998. environment variable, not the BOOTP server.
  999. CONFIG_BOOTP_MAY_FAIL - If the DHCP server is not found
  1000. after the configured retry count, the call will fail
  1001. instead of starting over. This can be used to fail over
  1002. to Link-local IP address configuration if the DHCP server
  1003. is not available.
  1004. CONFIG_BOOTP_DHCP_REQUEST_DELAY
  1005. A 32bit value in microseconds for a delay between
  1006. receiving a "DHCP Offer" and sending the "DHCP Request".
  1007. This fixes a problem with certain DHCP servers that don't
  1008. respond 100% of the time to a "DHCP request". E.g. On an
  1009. AT91RM9200 processor running at 180MHz, this delay needed
  1010. to be *at least* 15,000 usec before a Windows Server 2003
  1011. DHCP server would reply 100% of the time. I recommend at
  1012. least 50,000 usec to be safe. The alternative is to hope
  1013. that one of the retries will be successful but note that
  1014. the DHCP timeout and retry process takes a longer than
  1015. this delay.
  1016. - Link-local IP address negotiation:
  1017. Negotiate with other link-local clients on the local network
  1018. for an address that doesn't require explicit configuration.
  1019. This is especially useful if a DHCP server cannot be guaranteed
  1020. to exist in all environments that the device must operate.
  1021. See doc/README.link-local for more information.
  1022. - MAC address from environment variables
  1023. FDT_SEQ_MACADDR_FROM_ENV
  1024. Fix-up device tree with MAC addresses fetched sequentially from
  1025. environment variables. This config work on assumption that
  1026. non-usable ethernet node of device-tree are either not present
  1027. or their status has been marked as "disabled".
  1028. - CDP Options:
  1029. CONFIG_CDP_DEVICE_ID
  1030. The device id used in CDP trigger frames.
  1031. CONFIG_CDP_DEVICE_ID_PREFIX
  1032. A two character string which is prefixed to the MAC address
  1033. of the device.
  1034. CONFIG_CDP_PORT_ID
  1035. A printf format string which contains the ascii name of
  1036. the port. Normally is set to "eth%d" which sets
  1037. eth0 for the first Ethernet, eth1 for the second etc.
  1038. CONFIG_CDP_CAPABILITIES
  1039. A 32bit integer which indicates the device capabilities;
  1040. 0x00000010 for a normal host which does not forwards.
  1041. CONFIG_CDP_VERSION
  1042. An ascii string containing the version of the software.
  1043. CONFIG_CDP_PLATFORM
  1044. An ascii string containing the name of the platform.
  1045. CONFIG_CDP_TRIGGER
  1046. A 32bit integer sent on the trigger.
  1047. CONFIG_CDP_POWER_CONSUMPTION
  1048. A 16bit integer containing the power consumption of the
  1049. device in .1 of milliwatts.
  1050. CONFIG_CDP_APPLIANCE_VLAN_TYPE
  1051. A byte containing the id of the VLAN.
  1052. - Status LED: CONFIG_LED_STATUS
  1053. Several configurations allow to display the current
  1054. status using a LED. For instance, the LED will blink
  1055. fast while running U-Boot code, stop blinking as
  1056. soon as a reply to a BOOTP request was received, and
  1057. start blinking slow once the Linux kernel is running
  1058. (supported by a status LED driver in the Linux
  1059. kernel). Defining CONFIG_LED_STATUS enables this
  1060. feature in U-Boot.
  1061. Additional options:
  1062. CONFIG_LED_STATUS_GPIO
  1063. The status LED can be connected to a GPIO pin.
  1064. In such cases, the gpio_led driver can be used as a
  1065. status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
  1066. to include the gpio_led driver in the U-Boot binary.
  1067. CONFIG_GPIO_LED_INVERTED_TABLE
  1068. Some GPIO connected LEDs may have inverted polarity in which
  1069. case the GPIO high value corresponds to LED off state and
  1070. GPIO low value corresponds to LED on state.
  1071. In such cases CONFIG_GPIO_LED_INVERTED_TABLE may be defined
  1072. with a list of GPIO LEDs that have inverted polarity.
  1073. - I2C Support:
  1074. CONFIG_SYS_NUM_I2C_BUSES
  1075. Hold the number of i2c buses you want to use.
  1076. CONFIG_SYS_I2C_DIRECT_BUS
  1077. define this, if you don't use i2c muxes on your hardware.
  1078. if CONFIG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
  1079. omit this define.
  1080. CONFIG_SYS_I2C_MAX_HOPS
  1081. define how many muxes are maximal consecutively connected
  1082. on one i2c bus. If you not use i2c muxes, omit this
  1083. define.
  1084. CONFIG_SYS_I2C_BUSES
  1085. hold a list of buses you want to use, only used if
  1086. CONFIG_SYS_I2C_DIRECT_BUS is not defined, for example
  1087. a board with CONFIG_SYS_I2C_MAX_HOPS = 1 and
  1088. CONFIG_SYS_NUM_I2C_BUSES = 9:
  1089. CONFIG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
  1090. {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
  1091. {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
  1092. {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
  1093. {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
  1094. {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
  1095. {1, {I2C_NULL_HOP}}, \
  1096. {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
  1097. {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
  1098. }
  1099. which defines
  1100. bus 0 on adapter 0 without a mux
  1101. bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
  1102. bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
  1103. bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
  1104. bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
  1105. bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
  1106. bus 6 on adapter 1 without a mux
  1107. bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
  1108. bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
  1109. If you do not have i2c muxes on your board, omit this define.
  1110. - Legacy I2C Support:
  1111. If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
  1112. then the following macros need to be defined (examples are
  1113. from include/configs/lwmon.h):
  1114. I2C_INIT
  1115. (Optional). Any commands necessary to enable the I2C
  1116. controller or configure ports.
  1117. eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
  1118. I2C_ACTIVE
  1119. The code necessary to make the I2C data line active
  1120. (driven). If the data line is open collector, this
  1121. define can be null.
  1122. eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
  1123. I2C_TRISTATE
  1124. The code necessary to make the I2C data line tri-stated
  1125. (inactive). If the data line is open collector, this
  1126. define can be null.
  1127. eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
  1128. I2C_READ
  1129. Code that returns true if the I2C data line is high,
  1130. false if it is low.
  1131. eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
  1132. I2C_SDA(bit)
  1133. If <bit> is true, sets the I2C data line high. If it
  1134. is false, it clears it (low).
  1135. eg: #define I2C_SDA(bit) \
  1136. if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
  1137. else immr->im_cpm.cp_pbdat &= ~PB_SDA
  1138. I2C_SCL(bit)
  1139. If <bit> is true, sets the I2C clock line high. If it
  1140. is false, it clears it (low).
  1141. eg: #define I2C_SCL(bit) \
  1142. if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
  1143. else immr->im_cpm.cp_pbdat &= ~PB_SCL
  1144. I2C_DELAY
  1145. This delay is invoked four times per clock cycle so this
  1146. controls the rate of data transfer. The data rate thus
  1147. is 1 / (I2C_DELAY * 4). Often defined to be something
  1148. like:
  1149. #define I2C_DELAY udelay(2)
  1150. CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
  1151. If your arch supports the generic GPIO framework (asm/gpio.h),
  1152. then you may alternatively define the two GPIOs that are to be
  1153. used as SCL / SDA. Any of the previous I2C_xxx macros will
  1154. have GPIO-based defaults assigned to them as appropriate.
  1155. You should define these to the GPIO value as given directly to
  1156. the generic GPIO functions.
  1157. CONFIG_SYS_I2C_INIT_BOARD
  1158. When a board is reset during an i2c bus transfer
  1159. chips might think that the current transfer is still
  1160. in progress. On some boards it is possible to access
  1161. the i2c SCLK line directly, either by using the
  1162. processor pin as a GPIO or by having a second pin
  1163. connected to the bus. If this option is defined a
  1164. custom i2c_init_board() routine in boards/xxx/board.c
  1165. is run early in the boot sequence.
  1166. CONFIG_I2C_MULTI_BUS
  1167. This option allows the use of multiple I2C buses, each of which
  1168. must have a controller. At any point in time, only one bus is
  1169. active. To switch to a different bus, use the 'i2c dev' command.
  1170. Note that bus numbering is zero-based.
  1171. CONFIG_SYS_I2C_NOPROBES
  1172. This option specifies a list of I2C devices that will be skipped
  1173. when the 'i2c probe' command is issued. If CONFIG_I2C_MULTI_BUS
  1174. is set, specify a list of bus-device pairs. Otherwise, specify
  1175. a 1D array of device addresses
  1176. e.g.
  1177. #undef CONFIG_I2C_MULTI_BUS
  1178. #define CONFIG_SYS_I2C_NOPROBES {0x50,0x68}
  1179. will skip addresses 0x50 and 0x68 on a board with one I2C bus
  1180. #define CONFIG_I2C_MULTI_BUS
  1181. #define CONFIG_SYS_I2C_NOPROBES {{0,0x50},{0,0x68},{1,0x54}}
  1182. will skip addresses 0x50 and 0x68 on bus 0 and address 0x54 on bus 1
  1183. CONFIG_SYS_SPD_BUS_NUM
  1184. If defined, then this indicates the I2C bus number for DDR SPD.
  1185. If not defined, then U-Boot assumes that SPD is on I2C bus 0.
  1186. CONFIG_SYS_RTC_BUS_NUM
  1187. If defined, then this indicates the I2C bus number for the RTC.
  1188. If not defined, then U-Boot assumes that RTC is on I2C bus 0.
  1189. CONFIG_SOFT_I2C_READ_REPEATED_START
  1190. defining this will force the i2c_read() function in
  1191. the soft_i2c driver to perform an I2C repeated start
  1192. between writing the address pointer and reading the
  1193. data. If this define is omitted the default behaviour
  1194. of doing a stop-start sequence will be used. Most I2C
  1195. devices can use either method, but some require one or
  1196. the other.
  1197. - SPI Support: CONFIG_SPI
  1198. Enables SPI driver (so far only tested with
  1199. SPI EEPROM, also an instance works with Crystal A/D and
  1200. D/As on the SACSng board)
  1201. CONFIG_SOFT_SPI
  1202. Enables a software (bit-bang) SPI driver rather than
  1203. using hardware support. This is a general purpose
  1204. driver that only requires three general I/O port pins
  1205. (two outputs, one input) to function. If this is
  1206. defined, the board configuration must define several
  1207. SPI configuration items (port pins to use, etc). For
  1208. an example, see include/configs/sacsng.h.
  1209. CONFIG_SYS_SPI_MXC_WAIT
  1210. Timeout for waiting until spi transfer completed.
  1211. default: (CONFIG_SYS_HZ/100) /* 10 ms */
  1212. - FPGA Support: CONFIG_FPGA
  1213. Enables FPGA subsystem.
  1214. CONFIG_FPGA_<vendor>
  1215. Enables support for specific chip vendors.
  1216. (ALTERA, XILINX)
  1217. CONFIG_FPGA_<family>
  1218. Enables support for FPGA family.
  1219. (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
  1220. CONFIG_FPGA_COUNT
  1221. Specify the number of FPGA devices to support.
  1222. CONFIG_SYS_FPGA_PROG_FEEDBACK
  1223. Enable printing of hash marks during FPGA configuration.
  1224. CONFIG_SYS_FPGA_CHECK_BUSY
  1225. Enable checks on FPGA configuration interface busy
  1226. status by the configuration function. This option
  1227. will require a board or device specific function to
  1228. be written.
  1229. CONFIG_FPGA_DELAY
  1230. If defined, a function that provides delays in the FPGA
  1231. configuration driver.
  1232. CONFIG_SYS_FPGA_CHECK_CTRLC
  1233. Allow Control-C to interrupt FPGA configuration
  1234. CONFIG_SYS_FPGA_CHECK_ERROR
  1235. Check for configuration errors during FPGA bitfile
  1236. loading. For example, abort during Virtex II
  1237. configuration if the INIT_B line goes low (which
  1238. indicated a CRC error).
  1239. CONFIG_SYS_FPGA_WAIT_INIT
  1240. Maximum time to wait for the INIT_B line to de-assert
  1241. after PROB_B has been de-asserted during a Virtex II
  1242. FPGA configuration sequence. The default time is 500
  1243. ms.
  1244. CONFIG_SYS_FPGA_WAIT_BUSY
  1245. Maximum time to wait for BUSY to de-assert during
  1246. Virtex II FPGA configuration. The default is 5 ms.
  1247. CONFIG_SYS_FPGA_WAIT_CONFIG
  1248. Time to wait after FPGA configuration. The default is
  1249. 200 ms.
  1250. - Configuration Management:
  1251. CONFIG_IDENT_STRING
  1252. If defined, this string will be added to the U-Boot
  1253. version information (U_BOOT_VERSION)
  1254. - Vendor Parameter Protection:
  1255. U-Boot considers the values of the environment
  1256. variables "serial#" (Board Serial Number) and
  1257. "ethaddr" (Ethernet Address) to be parameters that
  1258. are set once by the board vendor / manufacturer, and
  1259. protects these variables from casual modification by
  1260. the user. Once set, these variables are read-only,
  1261. and write or delete attempts are rejected. You can
  1262. change this behaviour:
  1263. If CONFIG_ENV_OVERWRITE is #defined in your config
  1264. file, the write protection for vendor parameters is
  1265. completely disabled. Anybody can change or delete
  1266. these parameters.
  1267. Alternatively, if you define _both_ an ethaddr in the
  1268. default env _and_ CONFIG_OVERWRITE_ETHADDR_ONCE, a default
  1269. Ethernet address is installed in the environment,
  1270. which can be changed exactly ONCE by the user. [The
  1271. serial# is unaffected by this, i. e. it remains
  1272. read-only.]
  1273. The same can be accomplished in a more flexible way
  1274. for any variable by configuring the type of access
  1275. to allow for those variables in the ".flags" variable
  1276. or define CONFIG_ENV_FLAGS_LIST_STATIC.
  1277. - Protected RAM:
  1278. CONFIG_PRAM
  1279. Define this variable to enable the reservation of
  1280. "protected RAM", i. e. RAM which is not overwritten
  1281. by U-Boot. Define CONFIG_PRAM to hold the number of
  1282. kB you want to reserve for pRAM. You can overwrite
  1283. this default value by defining an environment
  1284. variable "pram" to the number of kB you want to
  1285. reserve. Note that the board info structure will
  1286. still show the full amount of RAM. If pRAM is
  1287. reserved, a new environment variable "mem" will
  1288. automatically be defined to hold the amount of
  1289. remaining RAM in a form that can be passed as boot
  1290. argument to Linux, for instance like that:
  1291. setenv bootargs ... mem=\${mem}
  1292. saveenv
  1293. This way you can tell Linux not to use this memory,
  1294. either, which results in a memory region that will
  1295. not be affected by reboots.
  1296. *WARNING* If your board configuration uses automatic
  1297. detection of the RAM size, you must make sure that
  1298. this memory test is non-destructive. So far, the
  1299. following board configurations are known to be
  1300. "pRAM-clean":
  1301. IVMS8, IVML24, SPD8xx,
  1302. HERMES, IP860, RPXlite, LWMON,
  1303. FLAGADM
  1304. - Access to physical memory region (> 4GB)
  1305. Some basic support is provided for operations on memory not
  1306. normally accessible to U-Boot - e.g. some architectures
  1307. support access to more than 4GB of memory on 32-bit
  1308. machines using physical address extension or similar.
  1309. Define CONFIG_PHYSMEM to access this basic support, which
  1310. currently only supports clearing the memory.
  1311. - Error Recovery:
  1312. CONFIG_NET_RETRY_COUNT
  1313. This variable defines the number of retries for
  1314. network operations like ARP, RARP, TFTP, or BOOTP
  1315. before giving up the operation. If not defined, a
  1316. default value of 5 is used.
  1317. CONFIG_ARP_TIMEOUT
  1318. Timeout waiting for an ARP reply in milliseconds.
  1319. CONFIG_NFS_TIMEOUT
  1320. Timeout in milliseconds used in NFS protocol.
  1321. If you encounter "ERROR: Cannot umount" in nfs command,
  1322. try longer timeout such as
  1323. #define CONFIG_NFS_TIMEOUT 10000UL
  1324. Note:
  1325. In the current implementation, the local variables
  1326. space and global environment variables space are
  1327. separated. Local variables are those you define by
  1328. simply typing `name=value'. To access a local
  1329. variable later on, you have write `$name' or
  1330. `${name}'; to execute the contents of a variable
  1331. directly type `$name' at the command prompt.
  1332. Global environment variables are those you use
  1333. setenv/printenv to work with. To run a command stored
  1334. in such a variable, you need to use the run command,
  1335. and you must not use the '$' sign to access them.
  1336. To store commands and special characters in a
  1337. variable, please use double quotation marks
  1338. surrounding the whole text of the variable, instead
  1339. of the backslashes before semicolons and special
  1340. symbols.
  1341. - Command Line Editing and History:
  1342. CONFIG_CMDLINE_PS_SUPPORT
  1343. Enable support for changing the command prompt string
  1344. at run-time. Only static string is supported so far.
  1345. The string is obtained from environment variables PS1
  1346. and PS2.
  1347. - Default Environment:
  1348. CONFIG_EXTRA_ENV_SETTINGS
  1349. Define this to contain any number of null terminated
  1350. strings (variable = value pairs) that will be part of
  1351. the default environment compiled into the boot image.
  1352. For example, place something like this in your
  1353. board's config file:
  1354. #define CONFIG_EXTRA_ENV_SETTINGS \
  1355. "myvar1=value1\0" \
  1356. "myvar2=value2\0"
  1357. Warning: This method is based on knowledge about the
  1358. internal format how the environment is stored by the
  1359. U-Boot code. This is NOT an official, exported
  1360. interface! Although it is unlikely that this format
  1361. will change soon, there is no guarantee either.
  1362. You better know what you are doing here.
  1363. Note: overly (ab)use of the default environment is
  1364. discouraged. Make sure to check other ways to preset
  1365. the environment like the "source" command or the
  1366. boot command first.
  1367. CONFIG_DELAY_ENVIRONMENT
  1368. Normally the environment is loaded when the board is
  1369. initialised so that it is available to U-Boot. This inhibits
  1370. that so that the environment is not available until
  1371. explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
  1372. this is instead controlled by the value of
  1373. /config/load-environment.
  1374. - TFTP Fixed UDP Port:
  1375. CONFIG_TFTP_PORT
  1376. If this is defined, the environment variable tftpsrcp
  1377. is used to supply the TFTP UDP source port value.
  1378. If tftpsrcp isn't defined, the normal pseudo-random port
  1379. number generator is used.
  1380. Also, the environment variable tftpdstp is used to supply
  1381. the TFTP UDP destination port value. If tftpdstp isn't
  1382. defined, the normal port 69 is used.
  1383. The purpose for tftpsrcp is to allow a TFTP server to
  1384. blindly start the TFTP transfer using the pre-configured
  1385. target IP address and UDP port. This has the effect of
  1386. "punching through" the (Windows XP) firewall, allowing
  1387. the remainder of the TFTP transfer to proceed normally.
  1388. A better solution is to properly configure the firewall,
  1389. but sometimes that is not allowed.
  1390. CONFIG_STANDALONE_LOAD_ADDR
  1391. This option defines a board specific value for the
  1392. address where standalone program gets loaded, thus
  1393. overwriting the architecture dependent default
  1394. settings.
  1395. - Frame Buffer Address:
  1396. CONFIG_FB_ADDR
  1397. Define CONFIG_FB_ADDR if you want to use specific
  1398. address for frame buffer. This is typically the case
  1399. when using a graphics controller has separate video
  1400. memory. U-Boot will then place the frame buffer at
  1401. the given address instead of dynamically reserving it
  1402. in system RAM by calling lcd_setmem(), which grabs
  1403. the memory for the frame buffer depending on the
  1404. configured panel size.
  1405. Please see board_init_f function.
  1406. - Automatic software updates via TFTP server
  1407. CONFIG_UPDATE_TFTP
  1408. CONFIG_UPDATE_TFTP_CNT_MAX
  1409. CONFIG_UPDATE_TFTP_MSEC_MAX
  1410. These options enable and control the auto-update feature;
  1411. for a more detailed description refer to doc/README.update.
  1412. - MTD Support (mtdparts command, UBI support)
  1413. CONFIG_MTD_UBI_WL_THRESHOLD
  1414. This parameter defines the maximum difference between the highest
  1415. erase counter value and the lowest erase counter value of eraseblocks
  1416. of UBI devices. When this threshold is exceeded, UBI starts performing
  1417. wear leveling by means of moving data from eraseblock with low erase
  1418. counter to eraseblocks with high erase counter.
  1419. The default value should be OK for SLC NAND flashes, NOR flashes and
  1420. other flashes which have eraseblock life-cycle 100000 or more.
  1421. However, in case of MLC NAND flashes which typically have eraseblock
  1422. life-cycle less than 10000, the threshold should be lessened (e.g.,
  1423. to 128 or 256, although it does not have to be power of 2).
  1424. default: 4096
  1425. CONFIG_MTD_UBI_BEB_LIMIT
  1426. This option specifies the maximum bad physical eraseblocks UBI
  1427. expects on the MTD device (per 1024 eraseblocks). If the
  1428. underlying flash does not admit of bad eraseblocks (e.g. NOR
  1429. flash), this value is ignored.
  1430. NAND datasheets often specify the minimum and maximum NVM
  1431. (Number of Valid Blocks) for the flashes' endurance lifetime.
  1432. The maximum expected bad eraseblocks per 1024 eraseblocks
  1433. then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
  1434. which gives 20 for most NANDs (MaxNVB is basically the total
  1435. count of eraseblocks on the chip).
  1436. To put it differently, if this value is 20, UBI will try to
  1437. reserve about 1.9% of physical eraseblocks for bad blocks
  1438. handling. And that will be 1.9% of eraseblocks on the entire
  1439. NAND chip, not just the MTD partition UBI attaches. This means
  1440. that if you have, say, a NAND flash chip admits maximum 40 bad
  1441. eraseblocks, and it is split on two MTD partitions of the same
  1442. size, UBI will reserve 40 eraseblocks when attaching a
  1443. partition.
  1444. default: 20
  1445. CONFIG_MTD_UBI_FASTMAP
  1446. Fastmap is a mechanism which allows attaching an UBI device
  1447. in nearly constant time. Instead of scanning the whole MTD device it
  1448. only has to locate a checkpoint (called fastmap) on the device.
  1449. The on-flash fastmap contains all information needed to attach
  1450. the device. Using fastmap makes only sense on large devices where
  1451. attaching by scanning takes long. UBI will not automatically install
  1452. a fastmap on old images, but you can set the UBI parameter
  1453. CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
  1454. that fastmap-enabled images are still usable with UBI implementations
  1455. without fastmap support. On typical flash devices the whole fastmap
  1456. fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
  1457. CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
  1458. Set this parameter to enable fastmap automatically on images
  1459. without a fastmap.
  1460. default: 0
  1461. CONFIG_MTD_UBI_FM_DEBUG
  1462. Enable UBI fastmap debug
  1463. default: 0
  1464. - SPL framework
  1465. CONFIG_SPL
  1466. Enable building of SPL globally.
  1467. CONFIG_SPL_LDSCRIPT
  1468. LDSCRIPT for linking the SPL binary.
  1469. CONFIG_SPL_MAX_FOOTPRINT
  1470. Maximum size in memory allocated to the SPL, BSS included.
  1471. When defined, the linker checks that the actual memory
  1472. used by SPL from _start to __bss_end does not exceed it.
  1473. CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
  1474. must not be both defined at the same time.
  1475. CONFIG_SPL_MAX_SIZE
  1476. Maximum size of the SPL image (text, data, rodata, and
  1477. linker lists sections), BSS excluded.
  1478. When defined, the linker checks that the actual size does
  1479. not exceed it.
  1480. CONFIG_SPL_RELOC_TEXT_BASE
  1481. Address to relocate to. If unspecified, this is equal to
  1482. CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).
  1483. CONFIG_SPL_BSS_START_ADDR
  1484. Link address for the BSS within the SPL binary.
  1485. CONFIG_SPL_BSS_MAX_SIZE
  1486. Maximum size in memory allocated to the SPL BSS.
  1487. When defined, the linker checks that the actual memory used
  1488. by SPL from __bss_start to __bss_end does not exceed it.
  1489. CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
  1490. must not be both defined at the same time.
  1491. CONFIG_SPL_STACK
  1492. Adress of the start of the stack SPL will use
  1493. CONFIG_SPL_PANIC_ON_RAW_IMAGE
  1494. When defined, SPL will panic() if the image it has
  1495. loaded does not have a signature.
  1496. Defining this is useful when code which loads images
  1497. in SPL cannot guarantee that absolutely all read errors
  1498. will be caught.
  1499. An example is the LPC32XX MLC NAND driver, which will
  1500. consider that a completely unreadable NAND block is bad,
  1501. and thus should be skipped silently.
  1502. CONFIG_SPL_RELOC_STACK
  1503. Adress of the start of the stack SPL will use after
  1504. relocation. If unspecified, this is equal to
  1505. CONFIG_SPL_STACK.
  1506. CONFIG_SYS_SPL_MALLOC_START
  1507. Starting address of the malloc pool used in SPL.
  1508. When this option is set the full malloc is used in SPL and
  1509. it is set up by spl_init() and before that, the simple malloc()
  1510. can be used if CONFIG_SYS_MALLOC_F is defined.
  1511. CONFIG_SYS_SPL_MALLOC_SIZE
  1512. The size of the malloc pool used in SPL.
  1513. CONFIG_SPL_OS_BOOT
  1514. Enable booting directly to an OS from SPL.
  1515. See also: doc/README.falcon
  1516. CONFIG_SPL_DISPLAY_PRINT
  1517. For ARM, enable an optional function to print more information
  1518. about the running system.
  1519. CONFIG_SPL_INIT_MINIMAL
  1520. Arch init code should be built for a very small image
  1521. CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
  1522. Partition on the MMC to load U-Boot from when the MMC is being
  1523. used in raw mode
  1524. CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
  1525. Sector to load kernel uImage from when MMC is being
  1526. used in raw mode (for Falcon mode)
  1527. CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
  1528. CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
  1529. Sector and number of sectors to load kernel argument
  1530. parameters from when MMC is being used in raw mode
  1531. (for falcon mode)
  1532. CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
  1533. Filename to read to load U-Boot when reading from filesystem
  1534. CONFIG_SPL_FS_LOAD_KERNEL_NAME
  1535. Filename to read to load kernel uImage when reading
  1536. from filesystem (for Falcon mode)
  1537. CONFIG_SPL_FS_LOAD_ARGS_NAME
  1538. Filename to read to load kernel argument parameters
  1539. when reading from filesystem (for Falcon mode)
  1540. CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
  1541. Set this for NAND SPL on PPC mpc83xx targets, so that
  1542. start.S waits for the rest of the SPL to load before
  1543. continuing (the hardware starts execution after just
  1544. loading the first page rather than the full 4K).
  1545. CONFIG_SPL_SKIP_RELOCATE
  1546. Avoid SPL relocation
  1547. CONFIG_SPL_NAND_IDENT
  1548. SPL uses the chip ID list to identify the NAND flash.
  1549. Requires CONFIG_SPL_NAND_BASE.
  1550. CONFIG_SPL_UBI
  1551. Support for a lightweight UBI (fastmap) scanner and
  1552. loader
  1553. CONFIG_SPL_NAND_RAW_ONLY
  1554. Support to boot only raw u-boot.bin images. Use this only
  1555. if you need to save space.
  1556. CONFIG_SPL_COMMON_INIT_DDR
  1557. Set for common ddr init with serial presence detect in
  1558. SPL binary.
  1559. CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
  1560. CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
  1561. CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
  1562. CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
  1563. CONFIG_SYS_NAND_ECCBYTES
  1564. Defines the size and behavior of the NAND that SPL uses
  1565. to read U-Boot
  1566. CONFIG_SYS_NAND_U_BOOT_DST
  1567. Location in memory to load U-Boot to
  1568. CONFIG_SYS_NAND_U_BOOT_SIZE
  1569. Size of image to load
  1570. CONFIG_SYS_NAND_U_BOOT_START
  1571. Entry point in loaded image to jump to
  1572. CONFIG_SYS_NAND_HW_ECC_OOBFIRST
  1573. Define this if you need to first read the OOB and then the
  1574. data. This is used, for example, on davinci platforms.
  1575. CONFIG_SPL_RAM_DEVICE
  1576. Support for running image already present in ram, in SPL binary
  1577. CONFIG_SPL_PAD_TO
  1578. Image offset to which the SPL should be padded before appending
  1579. the SPL payload. By default, this is defined as
  1580. CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
  1581. CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
  1582. payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
  1583. CONFIG_SPL_TARGET
  1584. Final target image containing SPL and payload. Some SPLs
  1585. use an arch-specific makefile fragment instead, for
  1586. example if more than one image needs to be produced.
  1587. CONFIG_SPL_FIT_PRINT
  1588. Printing information about a FIT image adds quite a bit of
  1589. code to SPL. So this is normally disabled in SPL. Use this
  1590. option to re-enable it. This will affect the output of the
  1591. bootm command when booting a FIT image.
  1592. - TPL framework
  1593. CONFIG_TPL
  1594. Enable building of TPL globally.
  1595. CONFIG_TPL_PAD_TO
  1596. Image offset to which the TPL should be padded before appending
  1597. the TPL payload. By default, this is defined as
  1598. CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
  1599. CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
  1600. payload without any padding, or >= CONFIG_SPL_MAX_SIZE.
  1601. - Interrupt support (PPC):
  1602. There are common interrupt_init() and timer_interrupt()
  1603. for all PPC archs. interrupt_init() calls interrupt_init_cpu()
  1604. for CPU specific initialization. interrupt_init_cpu()
  1605. should set decrementer_count to appropriate value. If
  1606. CPU resets decrementer automatically after interrupt
  1607. (ppc4xx) it should set decrementer_count to zero.
  1608. timer_interrupt() calls timer_interrupt_cpu() for CPU
  1609. specific handling. If board has watchdog / status_led
  1610. / other_activity_monitor it works automatically from
  1611. general timer_interrupt().
  1612. Board initialization settings:
  1613. ------------------------------
  1614. During Initialization u-boot calls a number of board specific functions
  1615. to allow the preparation of board specific prerequisites, e.g. pin setup
  1616. before drivers are initialized. To enable these callbacks the
  1617. following configuration macros have to be defined. Currently this is
  1618. architecture specific, so please check arch/your_architecture/lib/board.c
  1619. typically in board_init_f() and board_init_r().
  1620. - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
  1621. - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
  1622. - CONFIG_BOARD_LATE_INIT: Call board_late_init()
  1623. - CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()
  1624. Configuration Settings:
  1625. -----------------------
  1626. - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
  1627. Optionally it can be defined to support 64-bit memory commands.
  1628. - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
  1629. undefine this when you're short of memory.
  1630. - CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
  1631. width of the commands listed in the 'help' command output.
  1632. - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
  1633. prompt for user input.
  1634. - CONFIG_SYS_CBSIZE: Buffer size for input from the Console
  1635. - CONFIG_SYS_PBSIZE: Buffer size for Console output
  1636. - CONFIG_SYS_MAXARGS: max. Number of arguments accepted for monitor commands
  1637. - CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
  1638. the application (usually a Linux kernel) when it is
  1639. booted
  1640. - CONFIG_SYS_BAUDRATE_TABLE:
  1641. List of legal baudrate settings for this board.
  1642. - CONFIG_SYS_MEM_RESERVE_SECURE
  1643. Only implemented for ARMv8 for now.
  1644. If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
  1645. is substracted from total RAM and won't be reported to OS.
  1646. This memory can be used as secure memory. A variable
  1647. gd->arch.secure_ram is used to track the location. In systems
  1648. the RAM base is not zero, or RAM is divided into banks,
  1649. this variable needs to be recalcuated to get the address.
  1650. - CONFIG_SYS_MEM_TOP_HIDE:
  1651. If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
  1652. this specified memory area will get subtracted from the top
  1653. (end) of RAM and won't get "touched" at all by U-Boot. By
  1654. fixing up gd->ram_size the Linux kernel should gets passed
  1655. the now "corrected" memory size and won't touch it either.
  1656. This should work for arch/ppc and arch/powerpc. Only Linux
  1657. board ports in arch/powerpc with bootwrapper support that
  1658. recalculate the memory size from the SDRAM controller setup
  1659. will have to get fixed in Linux additionally.
  1660. This option can be used as a workaround for the 440EPx/GRx
  1661. CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
  1662. be touched.
  1663. WARNING: Please make sure that this value is a multiple of
  1664. the Linux page size (normally 4k). If this is not the case,
  1665. then the end address of the Linux memory will be located at a
  1666. non page size aligned address and this could cause major
  1667. problems.
  1668. - CONFIG_SYS_LOADS_BAUD_CHANGE:
  1669. Enable temporary baudrate change while serial download
  1670. - CONFIG_SYS_SDRAM_BASE:
  1671. Physical start address of SDRAM. _Must_ be 0 here.
  1672. - CONFIG_SYS_FLASH_BASE:
  1673. Physical start address of Flash memory.
  1674. - CONFIG_SYS_MONITOR_BASE:
  1675. Physical start address of boot monitor code (set by
  1676. make config files to be same as the text base address
  1677. (CONFIG_SYS_TEXT_BASE) used when linking) - same as
  1678. CONFIG_SYS_FLASH_BASE when booting from flash.
  1679. - CONFIG_SYS_MONITOR_LEN:
  1680. Size of memory reserved for monitor code, used to
  1681. determine _at_compile_time_ (!) if the environment is
  1682. embedded within the U-Boot image, or in a separate
  1683. flash sector.
  1684. - CONFIG_SYS_MALLOC_LEN:
  1685. Size of DRAM reserved for malloc() use.
  1686. - CONFIG_SYS_MALLOC_F_LEN
  1687. Size of the malloc() pool for use before relocation. If
  1688. this is defined, then a very simple malloc() implementation
  1689. will become available before relocation. The address is just
  1690. below the global data, and the stack is moved down to make
  1691. space.
  1692. This feature allocates regions with increasing addresses
  1693. within the region. calloc() is supported, but realloc()
  1694. is not available. free() is supported but does nothing.
  1695. The memory will be freed (or in fact just forgotten) when
  1696. U-Boot relocates itself.
  1697. - CONFIG_SYS_MALLOC_SIMPLE
  1698. Provides a simple and small malloc() and calloc() for those
  1699. boards which do not use the full malloc in SPL (which is
  1700. enabled with CONFIG_SYS_SPL_MALLOC_START).
  1701. - CONFIG_SYS_NONCACHED_MEMORY:
  1702. Size of non-cached memory area. This area of memory will be
  1703. typically located right below the malloc() area and mapped
  1704. uncached in the MMU. This is useful for drivers that would
  1705. otherwise require a lot of explicit cache maintenance. For
  1706. some drivers it's also impossible to properly maintain the
  1707. cache. For example if the regions that need to be flushed
  1708. are not a multiple of the cache-line size, *and* padding
  1709. cannot be allocated between the regions to align them (i.e.
  1710. if the HW requires a contiguous array of regions, and the
  1711. size of each region is not cache-aligned), then a flush of
  1712. one region may result in overwriting data that hardware has
  1713. written to another region in the same cache-line. This can
  1714. happen for example in network drivers where descriptors for
  1715. buffers are typically smaller than the CPU cache-line (e.g.
  1716. 16 bytes vs. 32 or 64 bytes).
  1717. Non-cached memory is only supported on 32-bit ARM at present.
  1718. - CONFIG_SYS_BOOTM_LEN:
  1719. Normally compressed uImages are limited to an
  1720. uncompressed size of 8 MBytes. If this is not enough,
  1721. you can define CONFIG_SYS_BOOTM_LEN in your board config file
  1722. to adjust this setting to your needs.
  1723. - CONFIG_SYS_BOOTMAPSZ:
  1724. Maximum size of memory mapped by the startup code of
  1725. the Linux kernel; all data that must be processed by
  1726. the Linux kernel (bd_info, boot arguments, FDT blob if
  1727. used) must be put below this limit, unless "bootm_low"
  1728. environment variable is defined and non-zero. In such case
  1729. all data for the Linux kernel must be between "bootm_low"
  1730. and "bootm_low" + CONFIG_SYS_BOOTMAPSZ. The environment
  1731. variable "bootm_mapsize" will override the value of
  1732. CONFIG_SYS_BOOTMAPSZ. If CONFIG_SYS_BOOTMAPSZ is undefined,
  1733. then the value in "bootm_size" will be used instead.
  1734. - CONFIG_SYS_BOOT_RAMDISK_HIGH:
  1735. Enable initrd_high functionality. If defined then the
  1736. initrd_high feature is enabled and the bootm ramdisk subcommand
  1737. is enabled.
  1738. - CONFIG_SYS_BOOT_GET_CMDLINE:
  1739. Enables allocating and saving kernel cmdline in space between
  1740. "bootm_low" and "bootm_low" + BOOTMAPSZ.
  1741. - CONFIG_SYS_BOOT_GET_KBD:
  1742. Enables allocating and saving a kernel copy of the bd_info in
  1743. space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
  1744. - CONFIG_SYS_MAX_FLASH_BANKS:
  1745. Max number of Flash memory banks
  1746. - CONFIG_SYS_MAX_FLASH_SECT:
  1747. Max number of sectors on a Flash chip
  1748. - CONFIG_SYS_FLASH_ERASE_TOUT:
  1749. Timeout for Flash erase operations (in ms)
  1750. - CONFIG_SYS_FLASH_WRITE_TOUT:
  1751. Timeout for Flash write operations (in ms)
  1752. - CONFIG_SYS_FLASH_LOCK_TOUT
  1753. Timeout for Flash set sector lock bit operation (in ms)
  1754. - CONFIG_SYS_FLASH_UNLOCK_TOUT
  1755. Timeout for Flash clear lock bits operation (in ms)
  1756. - CONFIG_SYS_FLASH_PROTECTION
  1757. If defined, hardware flash sectors protection is used
  1758. instead of U-Boot software protection.
  1759. - CONFIG_SYS_DIRECT_FLASH_TFTP:
  1760. Enable TFTP transfers directly to flash memory;
  1761. without this option such a download has to be
  1762. performed in two steps: (1) download to RAM, and (2)
  1763. copy from RAM to flash.
  1764. The two-step approach is usually more reliable, since
  1765. you can check if the download worked before you erase
  1766. the flash, but in some situations (when system RAM is
  1767. too limited to allow for a temporary copy of the
  1768. downloaded image) this option may be very useful.
  1769. - CONFIG_SYS_FLASH_CFI:
  1770. Define if the flash driver uses extra elements in the
  1771. common flash structure for storing flash geometry.
  1772. - CONFIG_FLASH_CFI_DRIVER
  1773. This option also enables the building of the cfi_flash driver
  1774. in the drivers directory
  1775. - CONFIG_FLASH_CFI_MTD
  1776. This option enables the building of the cfi_mtd driver
  1777. in the drivers directory. The driver exports CFI flash
  1778. to the MTD layer.
  1779. - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
  1780. Use buffered writes to flash.
  1781. - CONFIG_FLASH_SPANSION_S29WS_N
  1782. s29ws-n MirrorBit flash has non-standard addresses for buffered
  1783. write commands.
  1784. - CONFIG_SYS_FLASH_QUIET_TEST
  1785. If this option is defined, the common CFI flash doesn't
  1786. print it's warning upon not recognized FLASH banks. This
  1787. is useful, if some of the configured banks are only
  1788. optionally available.
  1789. - CONFIG_FLASH_SHOW_PROGRESS
  1790. If defined (must be an integer), print out countdown
  1791. digits and dots. Recommended value: 45 (9..1) for 80
  1792. column displays, 15 (3..1) for 40 column displays.
  1793. - CONFIG_FLASH_VERIFY
  1794. If defined, the content of the flash (destination) is compared
  1795. against the source after the write operation. An error message
  1796. will be printed when the contents are not identical.
  1797. Please note that this option is useless in nearly all cases,
  1798. since such flash programming errors usually are detected earlier
  1799. while unprotecting/erasing/programming. Please only enable
  1800. this option if you really know what you are doing.
  1801. - CONFIG_SYS_RX_ETH_BUFFER:
  1802. Defines the number of Ethernet receive buffers. On some
  1803. Ethernet controllers it is recommended to set this value
  1804. to 8 or even higher (EEPRO100 or 405 EMAC), since all
  1805. buffers can be full shortly after enabling the interface
  1806. on high Ethernet traffic.
  1807. Defaults to 4 if not defined.
  1808. - CONFIG_ENV_MAX_ENTRIES
  1809. Maximum number of entries in the hash table that is used
  1810. internally to store the environment settings. The default
  1811. setting is supposed to be generous and should work in most
  1812. cases. This setting can be used to tune behaviour; see
  1813. lib/hashtable.c for details.
  1814. - CONFIG_ENV_FLAGS_LIST_DEFAULT
  1815. - CONFIG_ENV_FLAGS_LIST_STATIC
  1816. Enable validation of the values given to environment variables when
  1817. calling env set. Variables can be restricted to only decimal,
  1818. hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
  1819. the variables can also be restricted to IP address or MAC address.
  1820. The format of the list is:
  1821. type_attribute = [s|d|x|b|i|m]
  1822. access_attribute = [a|r|o|c]
  1823. attributes = type_attribute[access_attribute]
  1824. entry = variable_name[:attributes]
  1825. list = entry[,list]
  1826. The type attributes are:
  1827. s - String (default)
  1828. d - Decimal
  1829. x - Hexadecimal
  1830. b - Boolean ([1yYtT|0nNfF])
  1831. i - IP address
  1832. m - MAC address
  1833. The access attributes are:
  1834. a - Any (default)
  1835. r - Read-only
  1836. o - Write-once
  1837. c - Change-default
  1838. - CONFIG_ENV_FLAGS_LIST_DEFAULT
  1839. Define this to a list (string) to define the ".flags"
  1840. environment variable in the default or embedded environment.
  1841. - CONFIG_ENV_FLAGS_LIST_STATIC
  1842. Define this to a list (string) to define validation that
  1843. should be done if an entry is not found in the ".flags"
  1844. environment variable. To override a setting in the static
  1845. list, simply add an entry for the same variable name to the
  1846. ".flags" variable.
  1847. If CONFIG_REGEX is defined, the variable_name above is evaluated as a
  1848. regular expression. This allows multiple variables to define the same
  1849. flags without explicitly listing them for each variable.
  1850. The following definitions that deal with the placement and management
  1851. of environment data (variable area); in general, we support the
  1852. following configurations:
  1853. - CONFIG_BUILD_ENVCRC:
  1854. Builds up envcrc with the target environment so that external utils
  1855. may easily extract it and embed it in final U-Boot images.
  1856. BE CAREFUL! The first access to the environment happens quite early
  1857. in U-Boot initialization (when we try to get the setting of for the
  1858. console baudrate). You *MUST* have mapped your NVRAM area then, or
  1859. U-Boot will hang.
  1860. Please note that even with NVRAM we still use a copy of the
  1861. environment in RAM: we could work on NVRAM directly, but we want to
  1862. keep settings there always unmodified except somebody uses "saveenv"
  1863. to save the current settings.
  1864. BE CAREFUL! For some special cases, the local device can not use
  1865. "saveenv" command. For example, the local device will get the
  1866. environment stored in a remote NOR flash by SRIO or PCIE link,
  1867. but it can not erase, write this NOR flash by SRIO or PCIE interface.
  1868. - CONFIG_NAND_ENV_DST
  1869. Defines address in RAM to which the nand_spl code should copy the
  1870. environment. If redundant environment is used, it will be copied to
  1871. CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
  1872. Please note that the environment is read-only until the monitor
  1873. has been relocated to RAM and a RAM copy of the environment has been
  1874. created; also, when using EEPROM you will have to use env_get_f()
  1875. until then to read environment variables.
  1876. The environment is protected by a CRC32 checksum. Before the monitor
  1877. is relocated into RAM, as a result of a bad CRC you will be working
  1878. with the compiled-in default environment - *silently*!!! [This is
  1879. necessary, because the first environment variable we need is the
  1880. "baudrate" setting for the console - if we have a bad CRC, we don't
  1881. have any device yet where we could complain.]
  1882. Note: once the monitor has been relocated, then it will complain if
  1883. the default environment is used; a new CRC is computed as soon as you
  1884. use the "saveenv" command to store a valid environment.
  1885. - CONFIG_SYS_FAULT_ECHO_LINK_DOWN:
  1886. Echo the inverted Ethernet link state to the fault LED.
  1887. Note: If this option is active, then CONFIG_SYS_FAULT_MII_ADDR
  1888. also needs to be defined.
  1889. - CONFIG_SYS_FAULT_MII_ADDR:
  1890. MII address of the PHY to check for the Ethernet link state.
  1891. - CONFIG_NS16550_MIN_FUNCTIONS:
  1892. Define this if you desire to only have use of the NS16550_init
  1893. and NS16550_putc functions for the serial driver located at
  1894. drivers/serial/ns16550.c. This option is useful for saving
  1895. space for already greatly restricted images, including but not
  1896. limited to NAND_SPL configurations.
  1897. - CONFIG_DISPLAY_BOARDINFO
  1898. Display information about the board that U-Boot is running on
  1899. when U-Boot starts up. The board function checkboard() is called
  1900. to do this.
  1901. - CONFIG_DISPLAY_BOARDINFO_LATE
  1902. Similar to the previous option, but display this information
  1903. later, once stdio is running and output goes to the LCD, if
  1904. present.
  1905. - CONFIG_BOARD_SIZE_LIMIT:
  1906. Maximum size of the U-Boot image. When defined, the
  1907. build system checks that the actual size does not
  1908. exceed it.
  1909. Low Level (hardware related) configuration options:
  1910. ---------------------------------------------------
  1911. - CONFIG_SYS_CACHELINE_SIZE:
  1912. Cache Line Size of the CPU.
  1913. - CONFIG_SYS_CCSRBAR_DEFAULT:
  1914. Default (power-on reset) physical address of CCSR on Freescale
  1915. PowerPC SOCs.
  1916. - CONFIG_SYS_CCSRBAR:
  1917. Virtual address of CCSR. On a 32-bit build, this is typically
  1918. the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
  1919. - CONFIG_SYS_CCSRBAR_PHYS:
  1920. Physical address of CCSR. CCSR can be relocated to a new
  1921. physical address, if desired. In this case, this macro should
  1922. be set to that address. Otherwise, it should be set to the
  1923. same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
  1924. is typically relocated on 36-bit builds. It is recommended
  1925. that this macro be defined via the _HIGH and _LOW macros:
  1926. #define CONFIG_SYS_CCSRBAR_PHYS ((CONFIG_SYS_CCSRBAR_PHYS_HIGH
  1927. * 1ull) << 32 | CONFIG_SYS_CCSRBAR_PHYS_LOW)
  1928. - CONFIG_SYS_CCSRBAR_PHYS_HIGH:
  1929. Bits 33-36 of CONFIG_SYS_CCSRBAR_PHYS. This value is typically
  1930. either 0 (32-bit build) or 0xF (36-bit build). This macro is
  1931. used in assembly code, so it must not contain typecasts or
  1932. integer size suffixes (e.g. "ULL").
  1933. - CONFIG_SYS_CCSRBAR_PHYS_LOW:
  1934. Lower 32-bits of CONFIG_SYS_CCSRBAR_PHYS. This macro is
  1935. used in assembly code, so it must not contain typecasts or
  1936. integer size suffixes (e.g. "ULL").
  1937. - CONFIG_SYS_CCSR_DO_NOT_RELOCATE:
  1938. If this macro is defined, then CONFIG_SYS_CCSRBAR_PHYS will be
  1939. forced to a value that ensures that CCSR is not relocated.
  1940. - CONFIG_IDE_AHB:
  1941. Most IDE controllers were designed to be connected with PCI
  1942. interface. Only few of them were designed for AHB interface.
  1943. When software is doing ATA command and data transfer to
  1944. IDE devices through IDE-AHB controller, some additional
  1945. registers accessing to these kind of IDE-AHB controller
  1946. is required.
  1947. - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
  1948. DO NOT CHANGE unless you know exactly what you're
  1949. doing! (11-4) [MPC8xx systems only]
  1950. - CONFIG_SYS_INIT_RAM_ADDR:
  1951. Start address of memory area that can be used for
  1952. initial data and stack; please note that this must be
  1953. writable memory that is working WITHOUT special
  1954. initialization, i. e. you CANNOT use normal RAM which
  1955. will become available only after programming the
  1956. memory controller and running certain initialization
  1957. sequences.
  1958. U-Boot uses the following memory types:
  1959. - MPC8xx: IMMR (internal memory of the CPU)
  1960. - CONFIG_SYS_GBL_DATA_OFFSET:
  1961. Offset of the initial data structure in the memory
  1962. area defined by CONFIG_SYS_INIT_RAM_ADDR. Usually
  1963. CONFIG_SYS_GBL_DATA_OFFSET is chosen such that the initial
  1964. data is located at the end of the available space
  1965. (sometimes written as (CONFIG_SYS_INIT_RAM_SIZE -
  1966. GENERATED_GBL_DATA_SIZE), and the initial stack is just
  1967. below that area (growing from (CONFIG_SYS_INIT_RAM_ADDR +
  1968. CONFIG_SYS_GBL_DATA_OFFSET) downward.
  1969. Note:
  1970. On the MPC824X (or other systems that use the data
  1971. cache for initial memory) the address chosen for
  1972. CONFIG_SYS_INIT_RAM_ADDR is basically arbitrary - it must
  1973. point to an otherwise UNUSED address space between
  1974. the top of RAM and the start of the PCI space.
  1975. - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
  1976. - CONFIG_SYS_OR_TIMING_SDRAM:
  1977. SDRAM timing
  1978. - CONFIG_SYS_MAMR_PTA:
  1979. periodic timer for refresh
  1980. - FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CONFIG_SYS_REMAP_OR_AM,
  1981. CONFIG_SYS_PRELIM_OR_AM, CONFIG_SYS_OR_TIMING_FLASH, CONFIG_SYS_OR0_REMAP,
  1982. CONFIG_SYS_OR0_PRELIM, CONFIG_SYS_BR0_PRELIM, CONFIG_SYS_OR1_REMAP, CONFIG_SYS_OR1_PRELIM,
  1983. CONFIG_SYS_BR1_PRELIM:
  1984. Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)
  1985. - SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
  1986. CONFIG_SYS_OR_TIMING_SDRAM, CONFIG_SYS_OR2_PRELIM, CONFIG_SYS_BR2_PRELIM,
  1987. CONFIG_SYS_OR3_PRELIM, CONFIG_SYS_BR3_PRELIM:
  1988. Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)
  1989. - CONFIG_SYS_SRIO:
  1990. Chip has SRIO or not
  1991. - CONFIG_SRIO1:
  1992. Board has SRIO 1 port available
  1993. - CONFIG_SRIO2:
  1994. Board has SRIO 2 port available
  1995. - CONFIG_SRIO_PCIE_BOOT_MASTER
  1996. Board can support master function for Boot from SRIO and PCIE
  1997. - CONFIG_SYS_SRIOn_MEM_VIRT:
  1998. Virtual Address of SRIO port 'n' memory region
  1999. - CONFIG_SYS_SRIOn_MEM_PHYxS:
  2000. Physical Address of SRIO port 'n' memory region
  2001. - CONFIG_SYS_SRIOn_MEM_SIZE:
  2002. Size of SRIO port 'n' memory region
  2003. - CONFIG_SYS_NAND_BUSWIDTH_16BIT
  2004. Defined to tell the NAND controller that the NAND chip is using
  2005. a 16 bit bus.
  2006. Not all NAND drivers use this symbol.
  2007. Example of drivers that use it:
  2008. - drivers/mtd/nand/raw/ndfc.c
  2009. - drivers/mtd/nand/raw/mxc_nand.c
  2010. - CONFIG_SYS_NDFC_EBC0_CFG
  2011. Sets the EBC0_CFG register for the NDFC. If not defined
  2012. a default value will be used.
  2013. - CONFIG_SPD_EEPROM
  2014. Get DDR timing information from an I2C EEPROM. Common
  2015. with pluggable memory modules such as SODIMMs
  2016. SPD_EEPROM_ADDRESS
  2017. I2C address of the SPD EEPROM
  2018. - CONFIG_SYS_SPD_BUS_NUM
  2019. If SPD EEPROM is on an I2C bus other than the first
  2020. one, specify here. Note that the value must resolve
  2021. to something your driver can deal with.
  2022. - CONFIG_SYS_DDR_RAW_TIMING
  2023. Get DDR timing information from other than SPD. Common with
  2024. soldered DDR chips onboard without SPD. DDR raw timing
  2025. parameters are extracted from datasheet and hard-coded into
  2026. header files or board specific files.
  2027. - CONFIG_FSL_DDR_INTERACTIVE
  2028. Enable interactive DDR debugging. See doc/README.fsl-ddr.
  2029. - CONFIG_FSL_DDR_SYNC_REFRESH
  2030. Enable sync of refresh for multiple controllers.
  2031. - CONFIG_FSL_DDR_BIST
  2032. Enable built-in memory test for Freescale DDR controllers.
  2033. - CONFIG_SYS_83XX_DDR_USES_CS0
  2034. Only for 83xx systems. If specified, then DDR should
  2035. be configured using CS0 and CS1 instead of CS2 and CS3.
  2036. - CONFIG_RMII
  2037. Enable RMII mode for all FECs.
  2038. Note that this is a global option, we can't
  2039. have one FEC in standard MII mode and another in RMII mode.
  2040. - CONFIG_CRC32_VERIFY
  2041. Add a verify option to the crc32 command.
  2042. The syntax is:
  2043. => crc32 -v <address> <count> <crc32>
  2044. Where address/count indicate a memory area
  2045. and crc32 is the correct crc32 which the
  2046. area should have.
  2047. - CONFIG_LOOPW
  2048. Add the "loopw" memory command. This only takes effect if
  2049. the memory commands are activated globally (CONFIG_CMD_MEMORY).
  2050. - CONFIG_CMD_MX_CYCLIC
  2051. Add the "mdc" and "mwc" memory commands. These are cyclic
  2052. "md/mw" commands.
  2053. Examples:
  2054. => mdc.b 10 4 500
  2055. This command will print 4 bytes (10,11,12,13) each 500 ms.
  2056. => mwc.l 100 12345678 10
  2057. This command will write 12345678 to address 100 all 10 ms.
  2058. This only takes effect if the memory commands are activated
  2059. globally (CONFIG_CMD_MEMORY).
  2060. - CONFIG_SPL_BUILD
  2061. Set when the currently-running compilation is for an artifact
  2062. that will end up in the SPL (as opposed to the TPL or U-Boot
  2063. proper). Code that needs stage-specific behavior should check
  2064. this.
  2065. - CONFIG_TPL_BUILD
  2066. Set when the currently-running compilation is for an artifact
  2067. that will end up in the TPL (as opposed to the SPL or U-Boot
  2068. proper). Code that needs stage-specific behavior should check
  2069. this.
  2070. - CONFIG_SYS_MPC85XX_NO_RESETVEC
  2071. Only for 85xx systems. If this variable is specified, the section
  2072. .resetvec is not kept and the section .bootpg is placed in the
  2073. previous 4k of the .text section.
  2074. - CONFIG_ARCH_MAP_SYSMEM
  2075. Generally U-Boot (and in particular the md command) uses
  2076. effective address. It is therefore not necessary to regard
  2077. U-Boot address as virtual addresses that need to be translated
  2078. to physical addresses. However, sandbox requires this, since
  2079. it maintains its own little RAM buffer which contains all
  2080. addressable memory. This option causes some memory accesses
  2081. to be mapped through map_sysmem() / unmap_sysmem().
  2082. - CONFIG_X86_RESET_VECTOR
  2083. If defined, the x86 reset vector code is included. This is not
  2084. needed when U-Boot is running from Coreboot.
  2085. - CONFIG_SYS_NAND_NO_SUBPAGE_WRITE
  2086. Option to disable subpage write in NAND driver
  2087. driver that uses this:
  2088. drivers/mtd/nand/raw/davinci_nand.c
  2089. Freescale QE/FMAN Firmware Support:
  2090. -----------------------------------
  2091. The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
  2092. loading of "firmware", which is encoded in the QE firmware binary format.
  2093. This firmware often needs to be loaded during U-Boot booting, so macros
  2094. are used to identify the storage device (NOR flash, SPI, etc) and the address
  2095. within that device.
  2096. - CONFIG_SYS_FMAN_FW_ADDR
  2097. The address in the storage device where the FMAN microcode is located. The
  2098. meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
  2099. is also specified.
  2100. - CONFIG_SYS_QE_FW_ADDR
  2101. The address in the storage device where the QE microcode is located. The
  2102. meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
  2103. is also specified.
  2104. - CONFIG_SYS_QE_FMAN_FW_LENGTH
  2105. The maximum possible size of the firmware. The firmware binary format
  2106. has a field that specifies the actual size of the firmware, but it
  2107. might not be possible to read any part of the firmware unless some
  2108. local storage is allocated to hold the entire firmware first.
  2109. - CONFIG_SYS_QE_FMAN_FW_IN_NOR
  2110. Specifies that QE/FMAN firmware is located in NOR flash, mapped as
  2111. normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
  2112. virtual address in NOR flash.
  2113. - CONFIG_SYS_QE_FMAN_FW_IN_NAND
  2114. Specifies that QE/FMAN firmware is located in NAND flash.
  2115. CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
  2116. - CONFIG_SYS_QE_FMAN_FW_IN_MMC
  2117. Specifies that QE/FMAN firmware is located on the primary SD/MMC
  2118. device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
  2119. - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
  2120. Specifies that QE/FMAN firmware is located in the remote (master)
  2121. memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
  2122. can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
  2123. window->master inbound window->master LAW->the ucode address in
  2124. master's memory space.
  2125. Freescale Layerscape Management Complex Firmware Support:
  2126. ---------------------------------------------------------
  2127. The Freescale Layerscape Management Complex (MC) supports the loading of
  2128. "firmware".
  2129. This firmware often needs to be loaded during U-Boot booting, so macros
  2130. are used to identify the storage device (NOR flash, SPI, etc) and the address
  2131. within that device.
  2132. - CONFIG_FSL_MC_ENET
  2133. Enable the MC driver for Layerscape SoCs.
  2134. Freescale Layerscape Debug Server Support:
  2135. -------------------------------------------
  2136. The Freescale Layerscape Debug Server Support supports the loading of
  2137. "Debug Server firmware" and triggering SP boot-rom.
  2138. This firmware often needs to be loaded during U-Boot booting.
  2139. - CONFIG_SYS_MC_RSV_MEM_ALIGN
  2140. Define alignment of reserved memory MC requires
  2141. Reproducible builds
  2142. -------------------
  2143. In order to achieve reproducible builds, timestamps used in the U-Boot build
  2144. process have to be set to a fixed value.
  2145. This is done using the SOURCE_DATE_EPOCH environment variable.
  2146. SOURCE_DATE_EPOCH is to be set on the build host's shell, not as a configuration
  2147. option for U-Boot or an environment variable in U-Boot.
  2148. SOURCE_DATE_EPOCH should be set to a number of seconds since the epoch, in UTC.
  2149. Building the Software:
  2150. ======================
  2151. Building U-Boot has been tested in several native build environments
  2152. and in many different cross environments. Of course we cannot support
  2153. all possibly existing versions of cross development tools in all
  2154. (potentially obsolete) versions. In case of tool chain problems we
  2155. recommend to use the ELDK (see https://www.denx.de/wiki/DULG/ELDK)
  2156. which is extensively used to build and test U-Boot.
  2157. If you are not using a native environment, it is assumed that you
  2158. have GNU cross compiling tools available in your path. In this case,
  2159. you must set the environment variable CROSS_COMPILE in your shell.
  2160. Note that no changes to the Makefile or any other source files are
  2161. necessary. For example using the ELDK on a 4xx CPU, please enter:
  2162. $ CROSS_COMPILE=ppc_4xx-
  2163. $ export CROSS_COMPILE
  2164. U-Boot is intended to be simple to build. After installing the
  2165. sources you must configure U-Boot for one specific board type. This
  2166. is done by typing:
  2167. make NAME_defconfig
  2168. where "NAME_defconfig" is the name of one of the existing configu-
  2169. rations; see configs/*_defconfig for supported names.
  2170. Note: for some boards special configuration names may exist; check if
  2171. additional information is available from the board vendor; for
  2172. instance, the TQM823L systems are available without (standard)
  2173. or with LCD support. You can select such additional "features"
  2174. when choosing the configuration, i. e.
  2175. make TQM823L_defconfig
  2176. - will configure for a plain TQM823L, i. e. no LCD support
  2177. make TQM823L_LCD_defconfig
  2178. - will configure for a TQM823L with U-Boot console on LCD
  2179. etc.
  2180. Finally, type "make all", and you should get some working U-Boot
  2181. images ready for download to / installation on your system:
  2182. - "u-boot.bin" is a raw binary image
  2183. - "u-boot" is an image in ELF binary format
  2184. - "u-boot.srec" is in Motorola S-Record format
  2185. By default the build is performed locally and the objects are saved
  2186. in the source directory. One of the two methods can be used to change
  2187. this behavior and build U-Boot to some external directory:
  2188. 1. Add O= to the make command line invocations:
  2189. make O=/tmp/build distclean
  2190. make O=/tmp/build NAME_defconfig
  2191. make O=/tmp/build all
  2192. 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
  2193. export KBUILD_OUTPUT=/tmp/build
  2194. make distclean
  2195. make NAME_defconfig
  2196. make all
  2197. Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
  2198. variable.
  2199. User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
  2200. setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
  2201. For example to treat all compiler warnings as errors:
  2202. make KCFLAGS=-Werror
  2203. Please be aware that the Makefiles assume you are using GNU make, so
  2204. for instance on NetBSD you might need to use "gmake" instead of
  2205. native "make".
  2206. If the system board that you have is not listed, then you will need
  2207. to port U-Boot to your hardware platform. To do this, follow these
  2208. steps:
  2209. 1. Create a new directory to hold your board specific code. Add any
  2210. files you need. In your board directory, you will need at least
  2211. the "Makefile" and a "<board>.c".
  2212. 2. Create a new configuration file "include/configs/<board>.h" for
  2213. your board.
  2214. 3. If you're porting U-Boot to a new CPU, then also create a new
  2215. directory to hold your CPU specific code. Add any files you need.
  2216. 4. Run "make <board>_defconfig" with your new name.
  2217. 5. Type "make", and you should get a working "u-boot.srec" file
  2218. to be installed on your target system.
  2219. 6. Debug and solve any problems that might arise.
  2220. [Of course, this last step is much harder than it sounds.]
  2221. Testing of U-Boot Modifications, Ports to New Hardware, etc.:
  2222. ==============================================================
  2223. If you have modified U-Boot sources (for instance added a new board
  2224. or support for new devices, a new CPU, etc.) you are expected to
  2225. provide feedback to the other developers. The feedback normally takes
  2226. the form of a "patch", i.e. a context diff against a certain (latest
  2227. official or latest in the git repository) version of U-Boot sources.
  2228. But before you submit such a patch, please verify that your modifi-
  2229. cation did not break existing code. At least make sure that *ALL* of
  2230. the supported boards compile WITHOUT ANY compiler warnings. To do so,
  2231. just run the buildman script (tools/buildman/buildman), which will
  2232. configure and build U-Boot for ALL supported system. Be warned, this
  2233. will take a while. Please see the buildman README, or run 'buildman -H'
  2234. for documentation.
  2235. See also "U-Boot Porting Guide" below.
  2236. Monitor Commands - Overview:
  2237. ============================
  2238. go - start application at address 'addr'
  2239. run - run commands in an environment variable
  2240. bootm - boot application image from memory
  2241. bootp - boot image via network using BootP/TFTP protocol
  2242. bootz - boot zImage from memory
  2243. tftpboot- boot image via network using TFTP protocol
  2244. and env variables "ipaddr" and "serverip"
  2245. (and eventually "gatewayip")
  2246. tftpput - upload a file via network using TFTP protocol
  2247. rarpboot- boot image via network using RARP/TFTP protocol
  2248. diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
  2249. loads - load S-Record file over serial line
  2250. loadb - load binary file over serial line (kermit mode)
  2251. md - memory display
  2252. mm - memory modify (auto-incrementing)
  2253. nm - memory modify (constant address)
  2254. mw - memory write (fill)
  2255. ms - memory search
  2256. cp - memory copy
  2257. cmp - memory compare
  2258. crc32 - checksum calculation
  2259. i2c - I2C sub-system
  2260. sspi - SPI utility commands
  2261. base - print or set address offset
  2262. printenv- print environment variables
  2263. pwm - control pwm channels
  2264. setenv - set environment variables
  2265. saveenv - save environment variables to persistent storage
  2266. protect - enable or disable FLASH write protection
  2267. erase - erase FLASH memory
  2268. flinfo - print FLASH memory information
  2269. nand - NAND memory operations (see doc/README.nand)
  2270. bdinfo - print Board Info structure
  2271. iminfo - print header information for application image
  2272. coninfo - print console devices and informations
  2273. ide - IDE sub-system
  2274. loop - infinite loop on address range
  2275. loopw - infinite write loop on address range
  2276. mtest - simple RAM test
  2277. icache - enable or disable instruction cache
  2278. dcache - enable or disable data cache
  2279. reset - Perform RESET of the CPU
  2280. echo - echo args to console
  2281. version - print monitor version
  2282. help - print online help
  2283. ? - alias for 'help'
  2284. Monitor Commands - Detailed Description:
  2285. ========================================
  2286. TODO.
  2287. For now: just type "help <command>".
  2288. Environment Variables:
  2289. ======================
  2290. U-Boot supports user configuration using Environment Variables which
  2291. can be made persistent by saving to Flash memory.
  2292. Environment Variables are set using "setenv", printed using
  2293. "printenv", and saved to Flash using "saveenv". Using "setenv"
  2294. without a value can be used to delete a variable from the
  2295. environment. As long as you don't save the environment you are
  2296. working with an in-memory copy. In case the Flash area containing the
  2297. environment is erased by accident, a default environment is provided.
  2298. Some configuration options can be set using Environment Variables.
  2299. List of environment variables (most likely not complete):
  2300. baudrate - see CONFIG_BAUDRATE
  2301. bootdelay - see CONFIG_BOOTDELAY
  2302. bootcmd - see CONFIG_BOOTCOMMAND
  2303. bootargs - Boot arguments when booting an RTOS image
  2304. bootfile - Name of the image to load with TFTP
  2305. bootm_low - Memory range available for image processing in the bootm
  2306. command can be restricted. This variable is given as
  2307. a hexadecimal number and defines lowest address allowed
  2308. for use by the bootm command. See also "bootm_size"
  2309. environment variable. Address defined by "bootm_low" is
  2310. also the base of the initial memory mapping for the Linux
  2311. kernel -- see the description of CONFIG_SYS_BOOTMAPSZ and
  2312. bootm_mapsize.
  2313. bootm_mapsize - Size of the initial memory mapping for the Linux kernel.
  2314. This variable is given as a hexadecimal number and it
  2315. defines the size of the memory region starting at base
  2316. address bootm_low that is accessible by the Linux kernel
  2317. during early boot. If unset, CONFIG_SYS_BOOTMAPSZ is used
  2318. as the default value if it is defined, and bootm_size is
  2319. used otherwise.
  2320. bootm_size - Memory range available for image processing in the bootm
  2321. command can be restricted. This variable is given as
  2322. a hexadecimal number and defines the size of the region
  2323. allowed for use by the bootm command. See also "bootm_low"
  2324. environment variable.
  2325. bootstopkeysha256, bootdelaykey, bootstopkey - See README.autoboot
  2326. updatefile - Location of the software update file on a TFTP server, used
  2327. by the automatic software update feature. Please refer to
  2328. documentation in doc/README.update for more details.
  2329. autoload - if set to "no" (any string beginning with 'n'),
  2330. "bootp" will just load perform a lookup of the
  2331. configuration from the BOOTP server, but not try to
  2332. load any image using TFTP
  2333. autostart - if set to "yes", an image loaded using the "bootp",
  2334. "rarpboot", "tftpboot" or "diskboot" commands will
  2335. be automatically started (by internally calling
  2336. "bootm")
  2337. If set to "no", a standalone image passed to the
  2338. "bootm" command will be copied to the load address
  2339. (and eventually uncompressed), but NOT be started.
  2340. This can be used to load and uncompress arbitrary
  2341. data.
  2342. fdt_high - if set this restricts the maximum address that the
  2343. flattened device tree will be copied into upon boot.
  2344. For example, if you have a system with 1 GB memory
  2345. at physical address 0x10000000, while Linux kernel
  2346. only recognizes the first 704 MB as low memory, you
  2347. may need to set fdt_high as 0x3C000000 to have the
  2348. device tree blob be copied to the maximum address
  2349. of the 704 MB low memory, so that Linux kernel can
  2350. access it during the boot procedure.
  2351. If this is set to the special value 0xFFFFFFFF then
  2352. the fdt will not be copied at all on boot. For this
  2353. to work it must reside in writable memory, have
  2354. sufficient padding on the end of it for u-boot to
  2355. add the information it needs into it, and the memory
  2356. must be accessible by the kernel.
  2357. fdtcontroladdr- if set this is the address of the control flattened
  2358. device tree used by U-Boot when CONFIG_OF_CONTROL is
  2359. defined.
  2360. i2cfast - (PPC405GP|PPC405EP only)
  2361. if set to 'y' configures Linux I2C driver for fast
  2362. mode (400kHZ). This environment variable is used in
  2363. initialization code. So, for changes to be effective
  2364. it must be saved and board must be reset.
  2365. initrd_high - restrict positioning of initrd images:
  2366. If this variable is not set, initrd images will be
  2367. copied to the highest possible address in RAM; this
  2368. is usually what you want since it allows for
  2369. maximum initrd size. If for some reason you want to
  2370. make sure that the initrd image is loaded below the
  2371. CONFIG_SYS_BOOTMAPSZ limit, you can set this environment
  2372. variable to a value of "no" or "off" or "0".
  2373. Alternatively, you can set it to a maximum upper
  2374. address to use (U-Boot will still check that it
  2375. does not overwrite the U-Boot stack and data).
  2376. For instance, when you have a system with 16 MB
  2377. RAM, and want to reserve 4 MB from use by Linux,
  2378. you can do this by adding "mem=12M" to the value of
  2379. the "bootargs" variable. However, now you must make
  2380. sure that the initrd image is placed in the first
  2381. 12 MB as well - this can be done with
  2382. setenv initrd_high 00c00000
  2383. If you set initrd_high to 0xFFFFFFFF, this is an
  2384. indication to U-Boot that all addresses are legal
  2385. for the Linux kernel, including addresses in flash
  2386. memory. In this case U-Boot will NOT COPY the
  2387. ramdisk at all. This may be useful to reduce the
  2388. boot time on your system, but requires that this
  2389. feature is supported by your Linux kernel.
  2390. ipaddr - IP address; needed for tftpboot command
  2391. loadaddr - Default load address for commands like "bootp",
  2392. "rarpboot", "tftpboot", "loadb" or "diskboot"
  2393. loads_echo - see CONFIG_LOADS_ECHO
  2394. serverip - TFTP server IP address; needed for tftpboot command
  2395. bootretry - see CONFIG_BOOT_RETRY_TIME
  2396. bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
  2397. bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
  2398. ethprime - controls which interface is used first.
  2399. ethact - controls which interface is currently active.
  2400. For example you can do the following
  2401. => setenv ethact FEC
  2402. => ping 192.168.0.1 # traffic sent on FEC
  2403. => setenv ethact SCC
  2404. => ping 10.0.0.1 # traffic sent on SCC
  2405. ethrotate - When set to "no" U-Boot does not go through all
  2406. available network interfaces.
  2407. It just stays at the currently selected interface.
  2408. netretry - When set to "no" each network operation will
  2409. either succeed or fail without retrying.
  2410. When set to "once" the network operation will
  2411. fail when all the available network interfaces
  2412. are tried once without success.
  2413. Useful on scripts which control the retry operation
  2414. themselves.
  2415. npe_ucode - set load address for the NPE microcode
  2416. silent_linux - If set then Linux will be told to boot silently, by
  2417. changing the console to be empty. If "yes" it will be
  2418. made silent. If "no" it will not be made silent. If
  2419. unset, then it will be made silent if the U-Boot console
  2420. is silent.
  2421. tftpsrcp - If this is set, the value is used for TFTP's
  2422. UDP source port.
  2423. tftpdstp - If this is set, the value is used for TFTP's UDP
  2424. destination port instead of the Well Know Port 69.
  2425. tftpblocksize - Block size to use for TFTP transfers; if not set,
  2426. we use the TFTP server's default block size
  2427. tftptimeout - Retransmission timeout for TFTP packets (in milli-
  2428. seconds, minimum value is 1000 = 1 second). Defines
  2429. when a packet is considered to be lost so it has to
  2430. be retransmitted. The default is 5000 = 5 seconds.
  2431. Lowering this value may make downloads succeed
  2432. faster in networks with high packet loss rates or
  2433. with unreliable TFTP servers.
  2434. tftptimeoutcountmax - maximum count of TFTP timeouts (no
  2435. unit, minimum value = 0). Defines how many timeouts
  2436. can happen during a single file transfer before that
  2437. transfer is aborted. The default is 10, and 0 means
  2438. 'no timeouts allowed'. Increasing this value may help
  2439. downloads succeed with high packet loss rates, or with
  2440. unreliable TFTP servers or client hardware.
  2441. tftpwindowsize - if this is set, the value is used for TFTP's
  2442. window size as described by RFC 7440.
  2443. This means the count of blocks we can receive before
  2444. sending ack to server.
  2445. vlan - When set to a value < 4095 the traffic over
  2446. Ethernet is encapsulated/received over 802.1q
  2447. VLAN tagged frames.
  2448. bootpretryperiod - Period during which BOOTP/DHCP sends retries.
  2449. Unsigned value, in milliseconds. If not set, the period will
  2450. be either the default (28000), or a value based on
  2451. CONFIG_NET_RETRY_COUNT, if defined. This value has
  2452. precedence over the valu based on CONFIG_NET_RETRY_COUNT.
  2453. memmatches - Number of matches found by the last 'ms' command, in hex
  2454. memaddr - Address of the last match found by the 'ms' command, in hex,
  2455. or 0 if none
  2456. mempos - Index position of the last match found by the 'ms' command,
  2457. in units of the size (.b, .w, .l) of the search
  2458. zbootbase - (x86 only) Base address of the bzImage 'setup' block
  2459. zbootaddr - (x86 only) Address of the loaded bzImage, typically
  2460. BZIMAGE_LOAD_ADDR which is 0x100000
  2461. The following image location variables contain the location of images
  2462. used in booting. The "Image" column gives the role of the image and is
  2463. not an environment variable name. The other columns are environment
  2464. variable names. "File Name" gives the name of the file on a TFTP
  2465. server, "RAM Address" gives the location in RAM the image will be
  2466. loaded to, and "Flash Location" gives the image's address in NOR
  2467. flash or offset in NAND flash.
  2468. *Note* - these variables don't have to be defined for all boards, some
  2469. boards currently use other variables for these purposes, and some
  2470. boards use these variables for other purposes.
  2471. Image File Name RAM Address Flash Location
  2472. ----- --------- ----------- --------------
  2473. u-boot u-boot u-boot_addr_r u-boot_addr
  2474. Linux kernel bootfile kernel_addr_r kernel_addr
  2475. device tree blob fdtfile fdt_addr_r fdt_addr
  2476. ramdisk ramdiskfile ramdisk_addr_r ramdisk_addr
  2477. The following environment variables may be used and automatically
  2478. updated by the network boot commands ("bootp" and "rarpboot"),
  2479. depending the information provided by your boot server:
  2480. bootfile - see above
  2481. dnsip - IP address of your Domain Name Server
  2482. dnsip2 - IP address of your secondary Domain Name Server
  2483. gatewayip - IP address of the Gateway (Router) to use
  2484. hostname - Target hostname
  2485. ipaddr - see above
  2486. netmask - Subnet Mask
  2487. rootpath - Pathname of the root filesystem on the NFS server
  2488. serverip - see above
  2489. There are two special Environment Variables:
  2490. serial# - contains hardware identification information such
  2491. as type string and/or serial number
  2492. ethaddr - Ethernet address
  2493. These variables can be set only once (usually during manufacturing of
  2494. the board). U-Boot refuses to delete or overwrite these variables
  2495. once they have been set once.
  2496. Further special Environment Variables:
  2497. ver - Contains the U-Boot version string as printed
  2498. with the "version" command. This variable is
  2499. readonly (see CONFIG_VERSION_VARIABLE).
  2500. Please note that changes to some configuration parameters may take
  2501. only effect after the next boot (yes, that's just like Windoze :-).
  2502. Callback functions for environment variables:
  2503. ---------------------------------------------
  2504. For some environment variables, the behavior of u-boot needs to change
  2505. when their values are changed. This functionality allows functions to
  2506. be associated with arbitrary variables. On creation, overwrite, or
  2507. deletion, the callback will provide the opportunity for some side
  2508. effect to happen or for the change to be rejected.
  2509. The callbacks are named and associated with a function using the
  2510. U_BOOT_ENV_CALLBACK macro in your board or driver code.
  2511. These callbacks are associated with variables in one of two ways. The
  2512. static list can be added to by defining CONFIG_ENV_CALLBACK_LIST_STATIC
  2513. in the board configuration to a string that defines a list of
  2514. associations. The list must be in the following format:
  2515. entry = variable_name[:callback_name]
  2516. list = entry[,list]
  2517. If the callback name is not specified, then the callback is deleted.
  2518. Spaces are also allowed anywhere in the list.
  2519. Callbacks can also be associated by defining the ".callbacks" variable
  2520. with the same list format above. Any association in ".callbacks" will
  2521. override any association in the static list. You can define
  2522. CONFIG_ENV_CALLBACK_LIST_DEFAULT to a list (string) to define the
  2523. ".callbacks" environment variable in the default or embedded environment.
  2524. If CONFIG_REGEX is defined, the variable_name above is evaluated as a
  2525. regular expression. This allows multiple variables to be connected to
  2526. the same callback without explicitly listing them all out.
  2527. The signature of the callback functions is:
  2528. int callback(const char *name, const char *value, enum env_op op, int flags)
  2529. * name - changed environment variable
  2530. * value - new value of the environment variable
  2531. * op - operation (create, overwrite, or delete)
  2532. * flags - attributes of the environment variable change, see flags H_* in
  2533. include/search.h
  2534. The return value is 0 if the variable change is accepted and 1 otherwise.
  2535. Note for Redundant Ethernet Interfaces:
  2536. =======================================
  2537. Some boards come with redundant Ethernet interfaces; U-Boot supports
  2538. such configurations and is capable of automatic selection of a
  2539. "working" interface when needed. MAC assignment works as follows:
  2540. Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
  2541. MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
  2542. "eth1addr" (=>eth1), "eth2addr", ...
  2543. If the network interface stores some valid MAC address (for instance
  2544. in SROM), this is used as default address if there is NO correspon-
  2545. ding setting in the environment; if the corresponding environment
  2546. variable is set, this overrides the settings in the card; that means:
  2547. o If the SROM has a valid MAC address, and there is no address in the
  2548. environment, the SROM's address is used.
  2549. o If there is no valid address in the SROM, and a definition in the
  2550. environment exists, then the value from the environment variable is
  2551. used.
  2552. o If both the SROM and the environment contain a MAC address, and
  2553. both addresses are the same, this MAC address is used.
  2554. o If both the SROM and the environment contain a MAC address, and the
  2555. addresses differ, the value from the environment is used and a
  2556. warning is printed.
  2557. o If neither SROM nor the environment contain a MAC address, an error
  2558. is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
  2559. a random, locally-assigned MAC is used.
  2560. If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
  2561. will be programmed into hardware as part of the initialization process. This
  2562. may be skipped by setting the appropriate 'ethmacskip' environment variable.
  2563. The naming convention is as follows:
  2564. "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
  2565. Image Formats:
  2566. ==============
  2567. U-Boot is capable of booting (and performing other auxiliary operations on)
  2568. images in two formats:
  2569. New uImage format (FIT)
  2570. -----------------------
  2571. Flexible and powerful format based on Flattened Image Tree -- FIT (similar
  2572. to Flattened Device Tree). It allows the use of images with multiple
  2573. components (several kernels, ramdisks, etc.), with contents protected by
  2574. SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
  2575. Old uImage format
  2576. -----------------
  2577. Old image format is based on binary files which can be basically anything,
  2578. preceded by a special header; see the definitions in include/image.h for
  2579. details; basically, the header defines the following image properties:
  2580. * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
  2581. 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
  2582. LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
  2583. Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, LynxOS,
  2584. INTEGRITY).
  2585. * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
  2586. IA64, MIPS, NDS32, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
  2587. Currently supported: ARM, Intel x86, MIPS, NDS32, Nios II, PowerPC).
  2588. * Compression Type (uncompressed, gzip, bzip2)
  2589. * Load Address
  2590. * Entry Point
  2591. * Image Name
  2592. * Image Timestamp
  2593. The header is marked by a special Magic Number, and both the header
  2594. and the data portions of the image are secured against corruption by
  2595. CRC32 checksums.
  2596. Linux Support:
  2597. ==============
  2598. Although U-Boot should support any OS or standalone application
  2599. easily, the main focus has always been on Linux during the design of
  2600. U-Boot.
  2601. U-Boot includes many features that so far have been part of some
  2602. special "boot loader" code within the Linux kernel. Also, any
  2603. "initrd" images to be used are no longer part of one big Linux image;
  2604. instead, kernel and "initrd" are separate images. This implementation
  2605. serves several purposes:
  2606. - the same features can be used for other OS or standalone
  2607. applications (for instance: using compressed images to reduce the
  2608. Flash memory footprint)
  2609. - it becomes much easier to port new Linux kernel versions because
  2610. lots of low-level, hardware dependent stuff are done by U-Boot
  2611. - the same Linux kernel image can now be used with different "initrd"
  2612. images; of course this also means that different kernel images can
  2613. be run with the same "initrd". This makes testing easier (you don't
  2614. have to build a new "zImage.initrd" Linux image when you just
  2615. change a file in your "initrd"). Also, a field-upgrade of the
  2616. software is easier now.
  2617. Linux HOWTO:
  2618. ============
  2619. Porting Linux to U-Boot based systems:
  2620. ---------------------------------------
  2621. U-Boot cannot save you from doing all the necessary modifications to
  2622. configure the Linux device drivers for use with your target hardware
  2623. (no, we don't intend to provide a full virtual machine interface to
  2624. Linux :-).
  2625. But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
  2626. Just make sure your machine specific header file (for instance
  2627. include/asm-ppc/tqm8xx.h) includes the same definition of the Board
  2628. Information structure as we define in include/asm-<arch>/u-boot.h,
  2629. and make sure that your definition of IMAP_ADDR uses the same value
  2630. as your U-Boot configuration in CONFIG_SYS_IMMR.
  2631. Note that U-Boot now has a driver model, a unified model for drivers.
  2632. If you are adding a new driver, plumb it into driver model. If there
  2633. is no uclass available, you are encouraged to create one. See
  2634. doc/driver-model.
  2635. Configuring the Linux kernel:
  2636. -----------------------------
  2637. No specific requirements for U-Boot. Make sure you have some root
  2638. device (initial ramdisk, NFS) for your target system.
  2639. Building a Linux Image:
  2640. -----------------------
  2641. With U-Boot, "normal" build targets like "zImage" or "bzImage" are
  2642. not used. If you use recent kernel source, a new build target
  2643. "uImage" will exist which automatically builds an image usable by
  2644. U-Boot. Most older kernels also have support for a "pImage" target,
  2645. which was introduced for our predecessor project PPCBoot and uses a
  2646. 100% compatible format.
  2647. Example:
  2648. make TQM850L_defconfig
  2649. make oldconfig
  2650. make dep
  2651. make uImage
  2652. The "uImage" build target uses a special tool (in 'tools/mkimage') to
  2653. encapsulate a compressed Linux kernel image with header information,
  2654. CRC32 checksum etc. for use with U-Boot. This is what we are doing:
  2655. * build a standard "vmlinux" kernel image (in ELF binary format):
  2656. * convert the kernel into a raw binary image:
  2657. ${CROSS_COMPILE}-objcopy -O binary \
  2658. -R .note -R .comment \
  2659. -S vmlinux linux.bin
  2660. * compress the binary image:
  2661. gzip -9 linux.bin
  2662. * package compressed binary image for U-Boot:
  2663. mkimage -A ppc -O linux -T kernel -C gzip \
  2664. -a 0 -e 0 -n "Linux Kernel Image" \
  2665. -d linux.bin.gz uImage
  2666. The "mkimage" tool can also be used to create ramdisk images for use
  2667. with U-Boot, either separated from the Linux kernel image, or
  2668. combined into one file. "mkimage" encapsulates the images with a 64
  2669. byte header containing information about target architecture,
  2670. operating system, image type, compression method, entry points, time
  2671. stamp, CRC32 checksums, etc.
  2672. "mkimage" can be called in two ways: to verify existing images and
  2673. print the header information, or to build new images.
  2674. In the first form (with "-l" option) mkimage lists the information
  2675. contained in the header of an existing U-Boot image; this includes
  2676. checksum verification:
  2677. tools/mkimage -l image
  2678. -l ==> list image header information
  2679. The second form (with "-d" option) is used to build a U-Boot image
  2680. from a "data file" which is used as image payload:
  2681. tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
  2682. -n name -d data_file image
  2683. -A ==> set architecture to 'arch'
  2684. -O ==> set operating system to 'os'
  2685. -T ==> set image type to 'type'
  2686. -C ==> set compression type 'comp'
  2687. -a ==> set load address to 'addr' (hex)
  2688. -e ==> set entry point to 'ep' (hex)
  2689. -n ==> set image name to 'name'
  2690. -d ==> use image data from 'datafile'
  2691. Right now, all Linux kernels for PowerPC systems use the same load
  2692. address (0x00000000), but the entry point address depends on the
  2693. kernel version:
  2694. - 2.2.x kernels have the entry point at 0x0000000C,
  2695. - 2.3.x and later kernels have the entry point at 0x00000000.
  2696. So a typical call to build a U-Boot image would read:
  2697. -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
  2698. > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
  2699. > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
  2700. > examples/uImage.TQM850L
  2701. Image Name: 2.4.4 kernel for TQM850L
  2702. Created: Wed Jul 19 02:34:59 2000
  2703. Image Type: PowerPC Linux Kernel Image (gzip compressed)
  2704. Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
  2705. Load Address: 0x00000000
  2706. Entry Point: 0x00000000
  2707. To verify the contents of the image (or check for corruption):
  2708. -> tools/mkimage -l examples/uImage.TQM850L
  2709. Image Name: 2.4.4 kernel for TQM850L
  2710. Created: Wed Jul 19 02:34:59 2000
  2711. Image Type: PowerPC Linux Kernel Image (gzip compressed)
  2712. Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
  2713. Load Address: 0x00000000
  2714. Entry Point: 0x00000000
  2715. NOTE: for embedded systems where boot time is critical you can trade
  2716. speed for memory and install an UNCOMPRESSED image instead: this
  2717. needs more space in Flash, but boots much faster since it does not
  2718. need to be uncompressed:
  2719. -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
  2720. -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
  2721. > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
  2722. > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
  2723. > examples/uImage.TQM850L-uncompressed
  2724. Image Name: 2.4.4 kernel for TQM850L
  2725. Created: Wed Jul 19 02:34:59 2000
  2726. Image Type: PowerPC Linux Kernel Image (uncompressed)
  2727. Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
  2728. Load Address: 0x00000000
  2729. Entry Point: 0x00000000
  2730. Similar you can build U-Boot images from a 'ramdisk.image.gz' file
  2731. when your kernel is intended to use an initial ramdisk:
  2732. -> tools/mkimage -n 'Simple Ramdisk Image' \
  2733. > -A ppc -O linux -T ramdisk -C gzip \
  2734. > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
  2735. Image Name: Simple Ramdisk Image
  2736. Created: Wed Jan 12 14:01:50 2000
  2737. Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
  2738. Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
  2739. Load Address: 0x00000000
  2740. Entry Point: 0x00000000
  2741. The "dumpimage" tool can be used to disassemble or list the contents of images
  2742. built by mkimage. See dumpimage's help output (-h) for details.
  2743. Installing a Linux Image:
  2744. -------------------------
  2745. To downloading a U-Boot image over the serial (console) interface,
  2746. you must convert the image to S-Record format:
  2747. objcopy -I binary -O srec examples/image examples/image.srec
  2748. The 'objcopy' does not understand the information in the U-Boot
  2749. image header, so the resulting S-Record file will be relative to
  2750. address 0x00000000. To load it to a given address, you need to
  2751. specify the target address as 'offset' parameter with the 'loads'
  2752. command.
  2753. Example: install the image to address 0x40100000 (which on the
  2754. TQM8xxL is in the first Flash bank):
  2755. => erase 40100000 401FFFFF
  2756. .......... done
  2757. Erased 8 sectors
  2758. => loads 40100000
  2759. ## Ready for S-Record download ...
  2760. ~>examples/image.srec
  2761. 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
  2762. ...
  2763. 15989 15990 15991 15992
  2764. [file transfer complete]
  2765. [connected]
  2766. ## Start Addr = 0x00000000
  2767. You can check the success of the download using the 'iminfo' command;
  2768. this includes a checksum verification so you can be sure no data
  2769. corruption happened:
  2770. => imi 40100000
  2771. ## Checking Image at 40100000 ...
  2772. Image Name: 2.2.13 for initrd on TQM850L
  2773. Image Type: PowerPC Linux Kernel Image (gzip compressed)
  2774. Data Size: 335725 Bytes = 327 kB = 0 MB
  2775. Load Address: 00000000
  2776. Entry Point: 0000000c
  2777. Verifying Checksum ... OK
  2778. Boot Linux:
  2779. -----------
  2780. The "bootm" command is used to boot an application that is stored in
  2781. memory (RAM or Flash). In case of a Linux kernel image, the contents
  2782. of the "bootargs" environment variable is passed to the kernel as
  2783. parameters. You can check and modify this variable using the
  2784. "printenv" and "setenv" commands:
  2785. => printenv bootargs
  2786. bootargs=root=/dev/ram
  2787. => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
  2788. => printenv bootargs
  2789. bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
  2790. => bootm 40020000
  2791. ## Booting Linux kernel at 40020000 ...
  2792. Image Name: 2.2.13 for NFS on TQM850L
  2793. Image Type: PowerPC Linux Kernel Image (gzip compressed)
  2794. Data Size: 381681 Bytes = 372 kB = 0 MB
  2795. Load Address: 00000000
  2796. Entry Point: 0000000c
  2797. Verifying Checksum ... OK
  2798. Uncompressing Kernel Image ... OK
  2799. Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:35:17 MEST 2000
  2800. Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
  2801. time_init: decrementer frequency = 187500000/60
  2802. Calibrating delay loop... 49.77 BogoMIPS
  2803. Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
  2804. ...
  2805. If you want to boot a Linux kernel with initial RAM disk, you pass
  2806. the memory addresses of both the kernel and the initrd image (PPBCOOT
  2807. format!) to the "bootm" command:
  2808. => imi 40100000 40200000
  2809. ## Checking Image at 40100000 ...
  2810. Image Name: 2.2.13 for initrd on TQM850L
  2811. Image Type: PowerPC Linux Kernel Image (gzip compressed)
  2812. Data Size: 335725 Bytes = 327 kB = 0 MB
  2813. Load Address: 00000000
  2814. Entry Point: 0000000c
  2815. Verifying Checksum ... OK
  2816. ## Checking Image at 40200000 ...
  2817. Image Name: Simple Ramdisk Image
  2818. Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
  2819. Data Size: 566530 Bytes = 553 kB = 0 MB
  2820. Load Address: 00000000
  2821. Entry Point: 00000000
  2822. Verifying Checksum ... OK
  2823. => bootm 40100000 40200000
  2824. ## Booting Linux kernel at 40100000 ...
  2825. Image Name: 2.2.13 for initrd on TQM850L
  2826. Image Type: PowerPC Linux Kernel Image (gzip compressed)
  2827. Data Size: 335725 Bytes = 327 kB = 0 MB
  2828. Load Address: 00000000
  2829. Entry Point: 0000000c
  2830. Verifying Checksum ... OK
  2831. Uncompressing Kernel Image ... OK
  2832. ## Loading RAMDisk Image at 40200000 ...
  2833. Image Name: Simple Ramdisk Image
  2834. Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
  2835. Data Size: 566530 Bytes = 553 kB = 0 MB
  2836. Load Address: 00000000
  2837. Entry Point: 00000000
  2838. Verifying Checksum ... OK
  2839. Loading Ramdisk ... OK
  2840. Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:32:08 MEST 2000
  2841. Boot arguments: root=/dev/ram
  2842. time_init: decrementer frequency = 187500000/60
  2843. Calibrating delay loop... 49.77 BogoMIPS
  2844. ...
  2845. RAMDISK: Compressed image found at block 0
  2846. VFS: Mounted root (ext2 filesystem).
  2847. bash#
  2848. Boot Linux and pass a flat device tree:
  2849. -----------
  2850. First, U-Boot must be compiled with the appropriate defines. See the section
  2851. titled "Linux Kernel Interface" above for a more in depth explanation. The
  2852. following is an example of how to start a kernel and pass an updated
  2853. flat device tree:
  2854. => print oftaddr
  2855. oftaddr=0x300000
  2856. => print oft
  2857. oft=oftrees/mpc8540ads.dtb
  2858. => tftp $oftaddr $oft
  2859. Speed: 1000, full duplex
  2860. Using TSEC0 device
  2861. TFTP from server 192.168.1.1; our IP address is 192.168.1.101
  2862. Filename 'oftrees/mpc8540ads.dtb'.
  2863. Load address: 0x300000
  2864. Loading: #
  2865. done
  2866. Bytes transferred = 4106 (100a hex)
  2867. => tftp $loadaddr $bootfile
  2868. Speed: 1000, full duplex
  2869. Using TSEC0 device
  2870. TFTP from server 192.168.1.1; our IP address is 192.168.1.2
  2871. Filename 'uImage'.
  2872. Load address: 0x200000
  2873. Loading:############
  2874. done
  2875. Bytes transferred = 1029407 (fb51f hex)
  2876. => print loadaddr
  2877. loadaddr=200000
  2878. => print oftaddr
  2879. oftaddr=0x300000
  2880. => bootm $loadaddr - $oftaddr
  2881. ## Booting image at 00200000 ...
  2882. Image Name: Linux-2.6.17-dirty
  2883. Image Type: PowerPC Linux Kernel Image (gzip compressed)
  2884. Data Size: 1029343 Bytes = 1005.2 kB
  2885. Load Address: 00000000
  2886. Entry Point: 00000000
  2887. Verifying Checksum ... OK
  2888. Uncompressing Kernel Image ... OK
  2889. Booting using flat device tree at 0x300000
  2890. Using MPC85xx ADS machine description
  2891. Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
  2892. [snip]
  2893. More About U-Boot Image Types:
  2894. ------------------------------
  2895. U-Boot supports the following image types:
  2896. "Standalone Programs" are directly runnable in the environment
  2897. provided by U-Boot; it is expected that (if they behave
  2898. well) you can continue to work in U-Boot after return from
  2899. the Standalone Program.
  2900. "OS Kernel Images" are usually images of some Embedded OS which
  2901. will take over control completely. Usually these programs
  2902. will install their own set of exception handlers, device
  2903. drivers, set up the MMU, etc. - this means, that you cannot
  2904. expect to re-enter U-Boot except by resetting the CPU.
  2905. "RAMDisk Images" are more or less just data blocks, and their
  2906. parameters (address, size) are passed to an OS kernel that is
  2907. being started.
  2908. "Multi-File Images" contain several images, typically an OS
  2909. (Linux) kernel image and one or more data images like
  2910. RAMDisks. This construct is useful for instance when you want
  2911. to boot over the network using BOOTP etc., where the boot
  2912. server provides just a single image file, but you want to get
  2913. for instance an OS kernel and a RAMDisk image.
  2914. "Multi-File Images" start with a list of image sizes, each
  2915. image size (in bytes) specified by an "uint32_t" in network
  2916. byte order. This list is terminated by an "(uint32_t)0".
  2917. Immediately after the terminating 0 follow the images, one by
  2918. one, all aligned on "uint32_t" boundaries (size rounded up to
  2919. a multiple of 4 bytes).
  2920. "Firmware Images" are binary images containing firmware (like
  2921. U-Boot or FPGA images) which usually will be programmed to
  2922. flash memory.
  2923. "Script files" are command sequences that will be executed by
  2924. U-Boot's command interpreter; this feature is especially
  2925. useful when you configure U-Boot to use a real shell (hush)
  2926. as command interpreter.
  2927. Booting the Linux zImage:
  2928. -------------------------
  2929. On some platforms, it's possible to boot Linux zImage. This is done
  2930. using the "bootz" command. The syntax of "bootz" command is the same
  2931. as the syntax of "bootm" command.
  2932. Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
  2933. kernel with raw initrd images. The syntax is slightly different, the
  2934. address of the initrd must be augmented by it's size, in the following
  2935. format: "<initrd addres>:<initrd size>".
  2936. Standalone HOWTO:
  2937. =================
  2938. One of the features of U-Boot is that you can dynamically load and
  2939. run "standalone" applications, which can use some resources of
  2940. U-Boot like console I/O functions or interrupt services.
  2941. Two simple examples are included with the sources:
  2942. "Hello World" Demo:
  2943. -------------------
  2944. 'examples/hello_world.c' contains a small "Hello World" Demo
  2945. application; it is automatically compiled when you build U-Boot.
  2946. It's configured to run at address 0x00040004, so you can play with it
  2947. like that:
  2948. => loads
  2949. ## Ready for S-Record download ...
  2950. ~>examples/hello_world.srec
  2951. 1 2 3 4 5 6 7 8 9 10 11 ...
  2952. [file transfer complete]
  2953. [connected]
  2954. ## Start Addr = 0x00040004
  2955. => go 40004 Hello World! This is a test.
  2956. ## Starting application at 0x00040004 ...
  2957. Hello World
  2958. argc = 7
  2959. argv[0] = "40004"
  2960. argv[1] = "Hello"
  2961. argv[2] = "World!"
  2962. argv[3] = "This"
  2963. argv[4] = "is"
  2964. argv[5] = "a"
  2965. argv[6] = "test."
  2966. argv[7] = "<NULL>"
  2967. Hit any key to exit ...
  2968. ## Application terminated, rc = 0x0
  2969. Another example, which demonstrates how to register a CPM interrupt
  2970. handler with the U-Boot code, can be found in 'examples/timer.c'.
  2971. Here, a CPM timer is set up to generate an interrupt every second.
  2972. The interrupt service routine is trivial, just printing a '.'
  2973. character, but this is just a demo program. The application can be
  2974. controlled by the following keys:
  2975. ? - print current values og the CPM Timer registers
  2976. b - enable interrupts and start timer
  2977. e - stop timer and disable interrupts
  2978. q - quit application
  2979. => loads
  2980. ## Ready for S-Record download ...
  2981. ~>examples/timer.srec
  2982. 1 2 3 4 5 6 7 8 9 10 11 ...
  2983. [file transfer complete]
  2984. [connected]
  2985. ## Start Addr = 0x00040004
  2986. => go 40004
  2987. ## Starting application at 0x00040004 ...
  2988. TIMERS=0xfff00980
  2989. Using timer 1
  2990. tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
  2991. Hit 'b':
  2992. [q, b, e, ?] Set interval 1000000 us
  2993. Enabling timer
  2994. Hit '?':
  2995. [q, b, e, ?] ........
  2996. tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
  2997. Hit '?':
  2998. [q, b, e, ?] .
  2999. tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
  3000. Hit '?':
  3001. [q, b, e, ?] .
  3002. tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
  3003. Hit '?':
  3004. [q, b, e, ?] .
  3005. tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
  3006. Hit 'e':
  3007. [q, b, e, ?] ...Stopping timer
  3008. Hit 'q':
  3009. [q, b, e, ?] ## Application terminated, rc = 0x0
  3010. Minicom warning:
  3011. ================
  3012. Over time, many people have reported problems when trying to use the
  3013. "minicom" terminal emulation program for serial download. I (wd)
  3014. consider minicom to be broken, and recommend not to use it. Under
  3015. Unix, I recommend to use C-Kermit for general purpose use (and
  3016. especially for kermit binary protocol download ("loadb" command), and
  3017. use "cu" for S-Record download ("loads" command). See
  3018. https://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.3.
  3019. for help with kermit.
  3020. Nevertheless, if you absolutely want to use it try adding this
  3021. configuration to your "File transfer protocols" section:
  3022. Name Program Name U/D FullScr IO-Red. Multi
  3023. X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
  3024. Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
  3025. NetBSD Notes:
  3026. =============
  3027. Starting at version 0.9.2, U-Boot supports NetBSD both as host
  3028. (build U-Boot) and target system (boots NetBSD/mpc8xx).
  3029. Building requires a cross environment; it is known to work on
  3030. NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
  3031. need gmake since the Makefiles are not compatible with BSD make).
  3032. Note that the cross-powerpc package does not install include files;
  3033. attempting to build U-Boot will fail because <machine/ansi.h> is
  3034. missing. This file has to be installed and patched manually:
  3035. # cd /usr/pkg/cross/powerpc-netbsd/include
  3036. # mkdir powerpc
  3037. # ln -s powerpc machine
  3038. # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
  3039. # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
  3040. Native builds *don't* work due to incompatibilities between native
  3041. and U-Boot include files.
  3042. Booting assumes that (the first part of) the image booted is a
  3043. stage-2 loader which in turn loads and then invokes the kernel
  3044. proper. Loader sources will eventually appear in the NetBSD source
  3045. tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
  3046. meantime, see ftp://ftp.denx.de/pub/u-boot/ppcboot_stage2.tar.gz
  3047. Implementation Internals:
  3048. =========================
  3049. The following is not intended to be a complete description of every
  3050. implementation detail. However, it should help to understand the
  3051. inner workings of U-Boot and make it easier to port it to custom
  3052. hardware.
  3053. Initial Stack, Global Data:
  3054. ---------------------------
  3055. The implementation of U-Boot is complicated by the fact that U-Boot
  3056. starts running out of ROM (flash memory), usually without access to
  3057. system RAM (because the memory controller is not initialized yet).
  3058. This means that we don't have writable Data or BSS segments, and BSS
  3059. is not initialized as zero. To be able to get a C environment working
  3060. at all, we have to allocate at least a minimal stack. Implementation
  3061. options for this are defined and restricted by the CPU used: Some CPU
  3062. models provide on-chip memory (like the IMMR area on MPC8xx and
  3063. MPC826x processors), on others (parts of) the data cache can be
  3064. locked as (mis-) used as memory, etc.
  3065. Chris Hallinan posted a good summary of these issues to the
  3066. U-Boot mailing list:
  3067. Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
  3068. From: "Chris Hallinan" <clh@net1plus.com>
  3069. Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
  3070. ...
  3071. Correct me if I'm wrong, folks, but the way I understand it
  3072. is this: Using DCACHE as initial RAM for Stack, etc, does not
  3073. require any physical RAM backing up the cache. The cleverness
  3074. is that the cache is being used as a temporary supply of
  3075. necessary storage before the SDRAM controller is setup. It's
  3076. beyond the scope of this list to explain the details, but you
  3077. can see how this works by studying the cache architecture and
  3078. operation in the architecture and processor-specific manuals.
  3079. OCM is On Chip Memory, which I believe the 405GP has 4K. It
  3080. is another option for the system designer to use as an
  3081. initial stack/RAM area prior to SDRAM being available. Either
  3082. option should work for you. Using CS 4 should be fine if your
  3083. board designers haven't used it for something that would
  3084. cause you grief during the initial boot! It is frequently not
  3085. used.
  3086. CONFIG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
  3087. with your processor/board/system design. The default value
  3088. you will find in any recent u-boot distribution in
  3089. walnut.h should work for you. I'd set it to a value larger
  3090. than your SDRAM module. If you have a 64MB SDRAM module, set
  3091. it above 400_0000. Just make sure your board has no resources
  3092. that are supposed to respond to that address! That code in
  3093. start.S has been around a while and should work as is when
  3094. you get the config right.
  3095. -Chris Hallinan
  3096. DS4.COM, Inc.
  3097. It is essential to remember this, since it has some impact on the C
  3098. code for the initialization procedures:
  3099. * Initialized global data (data segment) is read-only. Do not attempt
  3100. to write it.
  3101. * Do not use any uninitialized global data (or implicitly initialized
  3102. as zero data - BSS segment) at all - this is undefined, initiali-
  3103. zation is performed later (when relocating to RAM).
  3104. * Stack space is very limited. Avoid big data buffers or things like
  3105. that.
  3106. Having only the stack as writable memory limits means we cannot use
  3107. normal global data to share information between the code. But it
  3108. turned out that the implementation of U-Boot can be greatly
  3109. simplified by making a global data structure (gd_t) available to all
  3110. functions. We could pass a pointer to this data as argument to _all_
  3111. functions, but this would bloat the code. Instead we use a feature of
  3112. the GCC compiler (Global Register Variables) to share the data: we
  3113. place a pointer (gd) to the global data into a register which we
  3114. reserve for this purpose.
  3115. When choosing a register for such a purpose we are restricted by the
  3116. relevant (E)ABI specifications for the current architecture, and by
  3117. GCC's implementation.
  3118. For PowerPC, the following registers have specific use:
  3119. R1: stack pointer
  3120. R2: reserved for system use
  3121. R3-R4: parameter passing and return values
  3122. R5-R10: parameter passing
  3123. R13: small data area pointer
  3124. R30: GOT pointer
  3125. R31: frame pointer
  3126. (U-Boot also uses R12 as internal GOT pointer. r12
  3127. is a volatile register so r12 needs to be reset when
  3128. going back and forth between asm and C)
  3129. ==> U-Boot will use R2 to hold a pointer to the global data
  3130. Note: on PPC, we could use a static initializer (since the
  3131. address of the global data structure is known at compile time),
  3132. but it turned out that reserving a register results in somewhat
  3133. smaller code - although the code savings are not that big (on
  3134. average for all boards 752 bytes for the whole U-Boot image,
  3135. 624 text + 127 data).
  3136. On ARM, the following registers are used:
  3137. R0: function argument word/integer result
  3138. R1-R3: function argument word
  3139. R9: platform specific
  3140. R10: stack limit (used only if stack checking is enabled)
  3141. R11: argument (frame) pointer
  3142. R12: temporary workspace
  3143. R13: stack pointer
  3144. R14: link register
  3145. R15: program counter
  3146. ==> U-Boot will use R9 to hold a pointer to the global data
  3147. Note: on ARM, only R_ARM_RELATIVE relocations are supported.
  3148. On Nios II, the ABI is documented here:
  3149. https://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
  3150. ==> U-Boot will use gp to hold a pointer to the global data
  3151. Note: on Nios II, we give "-G0" option to gcc and don't use gp
  3152. to access small data sections, so gp is free.
  3153. On NDS32, the following registers are used:
  3154. R0-R1: argument/return
  3155. R2-R5: argument
  3156. R15: temporary register for assembler
  3157. R16: trampoline register
  3158. R28: frame pointer (FP)
  3159. R29: global pointer (GP)
  3160. R30: link register (LP)
  3161. R31: stack pointer (SP)
  3162. PC: program counter (PC)
  3163. ==> U-Boot will use R10 to hold a pointer to the global data
  3164. NOTE: DECLARE_GLOBAL_DATA_PTR must be used with file-global scope,
  3165. or current versions of GCC may "optimize" the code too much.
  3166. On RISC-V, the following registers are used:
  3167. x0: hard-wired zero (zero)
  3168. x1: return address (ra)
  3169. x2: stack pointer (sp)
  3170. x3: global pointer (gp)
  3171. x4: thread pointer (tp)
  3172. x5: link register (t0)
  3173. x8: frame pointer (fp)
  3174. x10-x11: arguments/return values (a0-1)
  3175. x12-x17: arguments (a2-7)
  3176. x28-31: temporaries (t3-6)
  3177. pc: program counter (pc)
  3178. ==> U-Boot will use gp to hold a pointer to the global data
  3179. Memory Management:
  3180. ------------------
  3181. U-Boot runs in system state and uses physical addresses, i.e. the
  3182. MMU is not used either for address mapping nor for memory protection.
  3183. The available memory is mapped to fixed addresses using the memory
  3184. controller. In this process, a contiguous block is formed for each
  3185. memory type (Flash, SDRAM, SRAM), even when it consists of several
  3186. physical memory banks.
  3187. U-Boot is installed in the first 128 kB of the first Flash bank (on
  3188. TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
  3189. booting and sizing and initializing DRAM, the code relocates itself
  3190. to the upper end of DRAM. Immediately below the U-Boot code some
  3191. memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
  3192. configuration setting]. Below that, a structure with global Board
  3193. Info data is placed, followed by the stack (growing downward).
  3194. Additionally, some exception handler code is copied to the low 8 kB
  3195. of DRAM (0x00000000 ... 0x00001FFF).
  3196. So a typical memory configuration with 16 MB of DRAM could look like
  3197. this:
  3198. 0x0000 0000 Exception Vector code
  3199. :
  3200. 0x0000 1FFF
  3201. 0x0000 2000 Free for Application Use
  3202. :
  3203. :
  3204. :
  3205. :
  3206. 0x00FB FF20 Monitor Stack (Growing downward)
  3207. 0x00FB FFAC Board Info Data and permanent copy of global data
  3208. 0x00FC 0000 Malloc Arena
  3209. :
  3210. 0x00FD FFFF
  3211. 0x00FE 0000 RAM Copy of Monitor Code
  3212. ... eventually: LCD or video framebuffer
  3213. ... eventually: pRAM (Protected RAM - unchanged by reset)
  3214. 0x00FF FFFF [End of RAM]
  3215. System Initialization:
  3216. ----------------------
  3217. In the reset configuration, U-Boot starts at the reset entry point
  3218. (on most PowerPC systems at address 0x00000100). Because of the reset
  3219. configuration for CS0# this is a mirror of the on board Flash memory.
  3220. To be able to re-map memory U-Boot then jumps to its link address.
  3221. To be able to implement the initialization code in C, a (small!)
  3222. initial stack is set up in the internal Dual Ported RAM (in case CPUs
  3223. which provide such a feature like), or in a locked part of the data
  3224. cache. After that, U-Boot initializes the CPU core, the caches and
  3225. the SIU.
  3226. Next, all (potentially) available memory banks are mapped using a
  3227. preliminary mapping. For example, we put them on 512 MB boundaries
  3228. (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
  3229. on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
  3230. programmed for SDRAM access. Using the temporary configuration, a
  3231. simple memory test is run that determines the size of the SDRAM
  3232. banks.
  3233. When there is more than one SDRAM bank, and the banks are of
  3234. different size, the largest is mapped first. For equal size, the first
  3235. bank (CS2#) is mapped first. The first mapping is always for address
  3236. 0x00000000, with any additional banks following immediately to create
  3237. contiguous memory starting from 0.
  3238. Then, the monitor installs itself at the upper end of the SDRAM area
  3239. and allocates memory for use by malloc() and for the global Board
  3240. Info data; also, the exception vector code is copied to the low RAM
  3241. pages, and the final stack is set up.
  3242. Only after this relocation will you have a "normal" C environment;
  3243. until that you are restricted in several ways, mostly because you are
  3244. running from ROM, and because the code will have to be relocated to a
  3245. new address in RAM.
  3246. U-Boot Porting Guide:
  3247. ----------------------
  3248. [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
  3249. list, October 2002]
  3250. int main(int argc, char *argv[])
  3251. {
  3252. sighandler_t no_more_time;
  3253. signal(SIGALRM, no_more_time);
  3254. alarm(PROJECT_DEADLINE - toSec (3 * WEEK));
  3255. if (available_money > available_manpower) {
  3256. Pay consultant to port U-Boot;
  3257. return 0;
  3258. }
  3259. Download latest U-Boot source;
  3260. Subscribe to u-boot mailing list;
  3261. if (clueless)
  3262. email("Hi, I am new to U-Boot, how do I get started?");
  3263. while (learning) {
  3264. Read the README file in the top level directory;
  3265. Read https://www.denx.de/wiki/bin/view/DULG/Manual;
  3266. Read applicable doc/README.*;
  3267. Read the source, Luke;
  3268. /* find . -name "*.[chS]" | xargs grep -i <keyword> */
  3269. }
  3270. if (available_money > toLocalCurrency ($2500))
  3271. Buy a BDI3000;
  3272. else
  3273. Add a lot of aggravation and time;
  3274. if (a similar board exists) { /* hopefully... */
  3275. cp -a board/<similar> board/<myboard>
  3276. cp include/configs/<similar>.h include/configs/<myboard>.h
  3277. } else {
  3278. Create your own board support subdirectory;
  3279. Create your own board include/configs/<myboard>.h file;
  3280. }
  3281. Edit new board/<myboard> files
  3282. Edit new include/configs/<myboard>.h
  3283. while (!accepted) {
  3284. while (!running) {
  3285. do {
  3286. Add / modify source code;
  3287. } until (compiles);
  3288. Debug;
  3289. if (clueless)
  3290. email("Hi, I am having problems...");
  3291. }
  3292. Send patch file to the U-Boot email list;
  3293. if (reasonable critiques)
  3294. Incorporate improvements from email list code review;
  3295. else
  3296. Defend code as written;
  3297. }
  3298. return 0;
  3299. }
  3300. void no_more_time (int sig)
  3301. {
  3302. hire_a_guru();
  3303. }
  3304. Coding Standards:
  3305. -----------------
  3306. All contributions to U-Boot should conform to the Linux kernel
  3307. coding style; see the kernel coding style guide at
  3308. https://www.kernel.org/doc/html/latest/process/coding-style.html, and the
  3309. script "scripts/Lindent" in your Linux kernel source directory.
  3310. Source files originating from a different project (for example the
  3311. MTD subsystem) are generally exempt from these guidelines and are not
  3312. reformatted to ease subsequent migration to newer versions of those
  3313. sources.
  3314. Please note that U-Boot is implemented in C (and to some small parts in
  3315. Assembler); no C++ is used, so please do not use C++ style comments (//)
  3316. in your code.
  3317. Please also stick to the following formatting rules:
  3318. - remove any trailing white space
  3319. - use TAB characters for indentation and vertical alignment, not spaces
  3320. - make sure NOT to use DOS '\r\n' line feeds
  3321. - do not add more than 2 consecutive empty lines to source files
  3322. - do not add trailing empty lines to source files
  3323. Submissions which do not conform to the standards may be returned
  3324. with a request to reformat the changes.
  3325. Submitting Patches:
  3326. -------------------
  3327. Since the number of patches for U-Boot is growing, we need to
  3328. establish some rules. Submissions which do not conform to these rules
  3329. may be rejected, even when they contain important and valuable stuff.
  3330. Please see https://www.denx.de/wiki/U-Boot/Patches for details.
  3331. Patches shall be sent to the u-boot mailing list <u-boot@lists.denx.de>;
  3332. see https://lists.denx.de/listinfo/u-boot
  3333. When you send a patch, please include the following information with
  3334. it:
  3335. * For bug fixes: a description of the bug and how your patch fixes
  3336. this bug. Please try to include a way of demonstrating that the
  3337. patch actually fixes something.
  3338. * For new features: a description of the feature and your
  3339. implementation.
  3340. * For major contributions, add a MAINTAINERS file with your
  3341. information and associated file and directory references.
  3342. * When you add support for a new board, don't forget to add a
  3343. maintainer e-mail address to the boards.cfg file, too.
  3344. * If your patch adds new configuration options, don't forget to
  3345. document these in the README file.
  3346. * The patch itself. If you are using git (which is *strongly*
  3347. recommended) you can easily generate the patch using the
  3348. "git format-patch". If you then use "git send-email" to send it to
  3349. the U-Boot mailing list, you will avoid most of the common problems
  3350. with some other mail clients.
  3351. If you cannot use git, use "diff -purN OLD NEW". If your version of
  3352. diff does not support these options, then get the latest version of
  3353. GNU diff.
  3354. The current directory when running this command shall be the parent
  3355. directory of the U-Boot source tree (i. e. please make sure that
  3356. your patch includes sufficient directory information for the
  3357. affected files).
  3358. We prefer patches as plain text. MIME attachments are discouraged,
  3359. and compressed attachments must not be used.
  3360. * If one logical set of modifications affects or creates several
  3361. files, all these changes shall be submitted in a SINGLE patch file.
  3362. * Changesets that contain different, unrelated modifications shall be
  3363. submitted as SEPARATE patches, one patch per changeset.
  3364. Notes:
  3365. * Before sending the patch, run the buildman script on your patched
  3366. source tree and make sure that no errors or warnings are reported
  3367. for any of the boards.
  3368. * Keep your modifications to the necessary minimum: A patch
  3369. containing several unrelated changes or arbitrary reformats will be
  3370. returned with a request to re-formatting / split it.
  3371. * If you modify existing code, make sure that your new code does not
  3372. add to the memory footprint of the code ;-) Small is beautiful!
  3373. When adding new features, these should compile conditionally only
  3374. (using #ifdef), and the resulting code with the new feature
  3375. disabled must not need more memory than the old code without your
  3376. modification.
  3377. * Remember that there is a size limit of 100 kB per message on the
  3378. u-boot mailing list. Bigger patches will be moderated. If they are
  3379. reasonable and not too big, they will be acknowledged. But patches
  3380. bigger than the size limit should be avoided.