12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970717273747576777879808182838485868788899091929394959697989910010110210310410510610710810911011111211311411511611711811912012112212312412512612712812913013113213313413513613713813914014114214314414514614714814915015115215315415515615715815916016116216316416516616716816917017117217317417517617717817918018118218318418518618718818919019119219319419519619719819920020120220320420520620720820921021121221321421521621721821922022122222322422522622722822923023123223323423523623723823924024124224324424524624724824925025125225325425525625725825926026126226326426526626726826927027127227327427527627727827928028128228328428528628728828929029129229329429529629729829930030130230330430530630730830931031131231331431531631731831932032132232332432532632732832933033133233333433533633733833934034134234334434534634734834935035135235335435535635735835936036136236336436536636736836937037137237337437537637737837938038138238338438538638738838939039139239339439539639739839940040140240340440540640740840941041141241341441541641741841942042142242342442542642742842943043143243343443543643743843944044144244344444544644744844945045145245345445545645745845946046146246346446546646746846947047147247347447547647747847948048148248348448548648748848949049149249349449549649749849950050150250350450550650750850951051151251351451551651751851952052152252352452552652752852953053153253353453553653753853954054154254354454554654754854955055155255355455555655755855956056156256356456556656756856957057157257357457557657757857958058158258358458558658758858959059159259359459559659759859960060160260360460560660760860961061161261361461561661761861962062162262362462562662762862963063163263363463563663763863964064164264364464564664764864965065165265365465565665765865966066166266366466566666766866967067167267367467567667767867968068168268368468568668768868969069169269369469569669769869970070170270370470570670770870971071171271371471571671771871972072172272372472572672772872973073173273373473573673773873974074174274374474574674774874975075175275375475575675775875976076176276376476576676776876977077177277377477577677777877978078178278378478578678778878979079179279379479579679779879980080180280380480580680780880981081181281381481581681781881982082182282382482582682782882983083183283383483583683783883984084184284384484584684784884985085185285385485585685785885986086186286386486586686786886987087187287387487587687787887988088188288388488588688788888989089189289389489589689789889990090190290390490590690790890991091191291391491591691791891992092192292392492592692792892993093193293393493593693793893994094194294394494594694794894995095195295395495595695795895996096196296396496596696796896997097197297397497597697797897998098198298398498598698798898999099199299399499599699799899910001001100210031004100510061007100810091010101110121013101410151016101710181019102010211022102310241025102610271028102910301031103210331034103510361037103810391040104110421043104410451046104710481049105010511052105310541055105610571058105910601061106210631064106510661067106810691070107110721073107410751076107710781079108010811082108310841085108610871088108910901091109210931094109510961097109810991100110111021103110411051106110711081109111011111112111311141115111611171118111911201121112211231124112511261127112811291130113111321133113411351136113711381139114011411142114311441145114611471148114911501151115211531154115511561157115811591160116111621163116411651166116711681169117011711172117311741175117611771178117911801181118211831184118511861187118811891190119111921193119411951196119711981199120012011202120312041205120612071208120912101211121212131214121512161217121812191220122112221223122412251226122712281229123012311232123312341235123612371238123912401241124212431244124512461247124812491250125112521253125412551256125712581259126012611262126312641265126612671268126912701271127212731274127512761277127812791280128112821283128412851286128712881289129012911292129312941295129612971298129913001301130213031304130513061307130813091310131113121313131413151316131713181319132013211322132313241325132613271328132913301331133213331334133513361337133813391340134113421343134413451346134713481349135013511352135313541355135613571358135913601361136213631364136513661367136813691370137113721373137413751376137713781379138013811382138313841385138613871388138913901391139213931394139513961397139813991400140114021403140414051406140714081409141014111412141314141415141614171418141914201421142214231424142514261427142814291430143114321433143414351436143714381439144014411442144314441445144614471448144914501451145214531454145514561457145814591460146114621463146414651466146714681469147014711472147314741475147614771478147914801481148214831484148514861487148814891490149114921493149414951496149714981499150015011502150315041505150615071508150915101511151215131514151515161517151815191520152115221523152415251526152715281529153015311532153315341535153615371538153915401541154215431544154515461547154815491550155115521553155415551556155715581559156015611562156315641565156615671568156915701571157215731574157515761577157815791580158115821583158415851586158715881589159015911592159315941595159615971598159916001601160216031604160516061607160816091610161116121613161416151616161716181619162016211622162316241625162616271628162916301631163216331634163516361637163816391640164116421643164416451646164716481649165016511652165316541655165616571658165916601661166216631664166516661667166816691670167116721673167416751676167716781679168016811682168316841685168616871688168916901691169216931694169516961697169816991700170117021703170417051706170717081709171017111712171317141715171617171718171917201721172217231724172517261727172817291730173117321733173417351736173717381739174017411742174317441745174617471748174917501751175217531754175517561757175817591760176117621763176417651766176717681769177017711772177317741775177617771778177917801781178217831784178517861787178817891790179117921793179417951796179717981799180018011802180318041805180618071808180918101811181218131814181518161817181818191820182118221823182418251826182718281829183018311832183318341835183618371838183918401841184218431844184518461847184818491850185118521853185418551856185718581859186018611862186318641865186618671868186918701871187218731874187518761877187818791880188118821883188418851886188718881889189018911892189318941895189618971898189919001901190219031904190519061907190819091910191119121913191419151916191719181919192019211922192319241925192619271928192919301931193219331934193519361937193819391940194119421943194419451946194719481949195019511952195319541955195619571958195919601961196219631964196519661967196819691970197119721973197419751976197719781979198019811982198319841985198619871988198919901991199219931994199519961997199819992000200120022003200420052006200720082009201020112012201320142015201620172018201920202021202220232024202520262027202820292030203120322033203420352036203720382039204020412042204320442045204620472048204920502051205220532054205520562057205820592060206120622063206420652066206720682069207020712072207320742075207620772078207920802081208220832084208520862087208820892090209120922093209420952096209720982099210021012102210321042105210621072108210921102111211221132114211521162117211821192120212121222123212421252126212721282129213021312132213321342135213621372138213921402141214221432144214521462147214821492150215121522153215421552156215721582159216021612162216321642165216621672168216921702171217221732174217521762177217821792180218121822183218421852186218721882189219021912192219321942195219621972198219922002201220222032204220522062207220822092210221122122213221422152216221722182219222022212222222322242225222622272228222922302231223222332234223522362237223822392240224122422243224422452246224722482249225022512252225322542255225622572258225922602261226222632264226522662267226822692270227122722273227422752276227722782279228022812282228322842285228622872288228922902291229222932294229522962297229822992300230123022303230423052306230723082309231023112312231323142315231623172318231923202321232223232324232523262327232823292330233123322333233423352336233723382339234023412342234323442345234623472348234923502351235223532354235523562357235823592360236123622363236423652366236723682369237023712372237323742375237623772378237923802381238223832384238523862387238823892390239123922393239423952396239723982399240024012402240324042405240624072408240924102411241224132414241524162417241824192420242124222423242424252426242724282429243024312432243324342435243624372438243924402441244224432444244524462447244824492450245124522453245424552456245724582459246024612462246324642465246624672468246924702471247224732474247524762477247824792480248124822483248424852486248724882489249024912492249324942495249624972498249925002501250225032504250525062507250825092510251125122513251425152516251725182519252025212522252325242525252625272528252925302531253225332534253525362537253825392540254125422543254425452546254725482549255025512552255325542555255625572558255925602561256225632564256525662567256825692570257125722573257425752576257725782579258025812582258325842585258625872588258925902591259225932594259525962597259825992600260126022603260426052606260726082609261026112612261326142615261626172618261926202621262226232624262526262627262826292630263126322633263426352636263726382639264026412642264326442645264626472648264926502651265226532654265526562657265826592660266126622663266426652666266726682669267026712672 |
- # SPDX-License-Identifier: GPL-2.0+
- #
- # (C) Copyright 2000 - 2013
- # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
- Summary:
- ========
- This directory contains the source code for U-Boot, a boot loader for
- Embedded boards based on PowerPC, ARM, MIPS and several other
- processors, which can be installed in a boot ROM and used to
- initialize and test the hardware or to download and run application
- code.
- The development of U-Boot is closely related to Linux: some parts of
- the source code originate in the Linux source tree, we have some
- header files in common, and special provision has been made to
- support booting of Linux images.
- Some attention has been paid to make this software easily
- configurable and extendable. For instance, all monitor commands are
- implemented with the same call interface, so that it's very easy to
- add new commands. Also, instead of permanently adding rarely used
- code (for instance hardware test utilities) to the monitor, you can
- load and run it dynamically.
- Status:
- =======
- In general, all boards for which a default configuration file exists in the
- configs/ directory have been tested to some extent and can be considered
- "working". In fact, many of them are used in production systems.
- In case of problems you can use
- scripts/get_maintainer.pl <path>
- to identify the people or companies responsible for various boards and
- subsystems. Or have a look at the git log.
- Where to get help:
- ==================
- In case you have questions about, problems with or contributions for
- U-Boot, you should send a message to the U-Boot mailing list at
- <u-boot@lists.denx.de>. There is also an archive of previous traffic
- on the mailing list - please search the archive before asking FAQ's.
- Please see https://lists.denx.de/pipermail/u-boot and
- https://marc.info/?l=u-boot
- Where to get source code:
- =========================
- The U-Boot source code is maintained in the Git repository at
- https://source.denx.de/u-boot/u-boot.git ; you can browse it online at
- https://source.denx.de/u-boot/u-boot
- The "Tags" links on this page allow you to download tarballs of
- any version you might be interested in. Official releases are also
- available from the DENX file server through HTTPS or FTP.
- https://ftp.denx.de/pub/u-boot/
- ftp://ftp.denx.de/pub/u-boot/
- Where we come from:
- ===================
- - start from 8xxrom sources
- - create PPCBoot project (https://sourceforge.net/projects/ppcboot)
- - clean up code
- - make it easier to add custom boards
- - make it possible to add other [PowerPC] CPUs
- - extend functions, especially:
- * Provide extended interface to Linux boot loader
- * S-Record download
- * network boot
- * ATA disk / SCSI ... boot
- - create ARMBoot project (https://sourceforge.net/projects/armboot)
- - add other CPU families (starting with ARM)
- - create U-Boot project (https://sourceforge.net/projects/u-boot)
- - current project page: see https://www.denx.de/wiki/U-Boot
- Names and Spelling:
- ===================
- The "official" name of this project is "Das U-Boot". The spelling
- "U-Boot" shall be used in all written text (documentation, comments
- in source files etc.). Example:
- This is the README file for the U-Boot project.
- File names etc. shall be based on the string "u-boot". Examples:
- include/asm-ppc/u-boot.h
- #include <asm/u-boot.h>
- Variable names, preprocessor constants etc. shall be either based on
- the string "u_boot" or on "U_BOOT". Example:
- U_BOOT_VERSION u_boot_logo
- IH_OS_U_BOOT u_boot_hush_start
- Software Configuration:
- =======================
- Selection of Processor Architecture and Board Type:
- ---------------------------------------------------
- For all supported boards there are ready-to-use default
- configurations available; just type "make <board_name>_defconfig".
- Example: For a TQM823L module type:
- cd u-boot
- make TQM823L_defconfig
- Note: If you're looking for the default configuration file for a board
- you're sure used to be there but is now missing, check the file
- doc/README.scrapyard for a list of no longer supported boards.
- Sandbox Environment:
- --------------------
- U-Boot can be built natively to run on a Linux host using the 'sandbox'
- board. This allows feature development which is not board- or architecture-
- specific to be undertaken on a native platform. The sandbox is also used to
- run some of U-Boot's tests.
- See doc/arch/sandbox/sandbox.rst for more details.
- Board Initialisation Flow:
- --------------------------
- This is the intended start-up flow for boards. This should apply for both
- SPL and U-Boot proper (i.e. they both follow the same rules).
- Note: "SPL" stands for "Secondary Program Loader," which is explained in
- more detail later in this file.
- At present, SPL mostly uses a separate code path, but the function names
- and roles of each function are the same. Some boards or architectures
- may not conform to this. At least most ARM boards which use
- CONFIG_SPL_FRAMEWORK conform to this.
- Execution typically starts with an architecture-specific (and possibly
- CPU-specific) start.S file, such as:
- - arch/arm/cpu/armv7/start.S
- - arch/powerpc/cpu/mpc83xx/start.S
- - arch/mips/cpu/start.S
- and so on. From there, three functions are called; the purpose and
- limitations of each of these functions are described below.
- lowlevel_init():
- - purpose: essential init to permit execution to reach board_init_f()
- - no global_data or BSS
- - there is no stack (ARMv7 may have one but it will soon be removed)
- - must not set up SDRAM or use console
- - must only do the bare minimum to allow execution to continue to
- board_init_f()
- - this is almost never needed
- - return normally from this function
- board_init_f():
- - purpose: set up the machine ready for running board_init_r():
- i.e. SDRAM and serial UART
- - global_data is available
- - stack is in SRAM
- - BSS is not available, so you cannot use global/static variables,
- only stack variables and global_data
- Non-SPL-specific notes:
- - dram_init() is called to set up DRAM. If already done in SPL this
- can do nothing
- SPL-specific notes:
- - you can override the entire board_init_f() function with your own
- version as needed.
- - preloader_console_init() can be called here in extremis
- - should set up SDRAM, and anything needed to make the UART work
- - there is no need to clear BSS, it will be done by crt0.S
- - for specific scenarios on certain architectures an early BSS *can*
- be made available (via CONFIG_SPL_EARLY_BSS by moving the clearing
- of BSS prior to entering board_init_f()) but doing so is discouraged.
- Instead it is strongly recommended to architect any code changes
- or additions such to not depend on the availability of BSS during
- board_init_f() as indicated in other sections of this README to
- maintain compatibility and consistency across the entire code base.
- - must return normally from this function (don't call board_init_r()
- directly)
- Here the BSS is cleared. For SPL, if CONFIG_SPL_STACK_R is defined, then at
- this point the stack and global_data are relocated to below
- CONFIG_SPL_STACK_R_ADDR. For non-SPL, U-Boot is relocated to run at the top of
- memory.
- board_init_r():
- - purpose: main execution, common code
- - global_data is available
- - SDRAM is available
- - BSS is available, all static/global variables can be used
- - execution eventually continues to main_loop()
- Non-SPL-specific notes:
- - U-Boot is relocated to the top of memory and is now running from
- there.
- SPL-specific notes:
- - stack is optionally in SDRAM, if CONFIG_SPL_STACK_R is defined and
- CONFIG_SYS_FSL_HAS_CCI400
- Defined For SoC that has cache coherent interconnect
- CCN-400
- CONFIG_SYS_FSL_HAS_CCN504
- Defined for SoC that has cache coherent interconnect CCN-504
- The following options need to be configured:
- - CPU Type: Define exactly one, e.g. CONFIG_MPC85XX.
- - Board Type: Define exactly one, e.g. CONFIG_MPC8540ADS.
- - 85xx CPU Options:
- CONFIG_SYS_PPC64
- Specifies that the core is a 64-bit PowerPC implementation (implements
- the "64" category of the Power ISA). This is necessary for ePAPR
- compliance, among other possible reasons.
- CONFIG_SYS_FSL_ERRATUM_A004510
- Enables a workaround for erratum A004510. If set,
- then CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV and
- CFG_SYS_FSL_CORENET_SNOOPVEC_COREONLY must be set.
- CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV
- CONFIG_SYS_FSL_ERRATUM_A004510_SVR_REV2 (optional)
- Defines one or two SoC revisions (low 8 bits of SVR)
- for which the A004510 workaround should be applied.
- The rest of SVR is either not relevant to the decision
- of whether the erratum is present (e.g. p2040 versus
- p2041) or is implied by the build target, which controls
- whether CONFIG_SYS_FSL_ERRATUM_A004510 is set.
- See Freescale App Note 4493 for more information about
- this erratum.
- CFG_SYS_FSL_CORENET_SNOOPVEC_COREONLY
- This is the value to write into CCSR offset 0x18600
- according to the A004510 workaround.
- CONFIG_SYS_FSL_SINGLE_SOURCE_CLK
- Single Source Clock is clocking mode present in some of FSL SoC's.
- In this mode, a single differential clock is used to supply
- clocks to the sysclock, ddrclock and usbclock.
- - Generic CPU options:
- CONFIG_SYS_FSL_DDR
- Freescale DDR driver in use. This type of DDR controller is
- found in mpc83xx, mpc85xx as well as some ARM core SoCs.
- CFG_SYS_FSL_DDR_ADDR
- Freescale DDR memory-mapped register base.
- CONFIG_SYS_FSL_IFC_CLK_DIV
- Defines divider of platform clock(clock input to IFC controller).
- CONFIG_SYS_FSL_LBC_CLK_DIV
- Defines divider of platform clock(clock input to eLBC controller).
- CFG_SYS_FSL_DDR_SDRAM_BASE_PHY
- Physical address from the view of DDR controllers. It is the
- same as CFG_SYS_DDR_SDRAM_BASE for all Power SoCs. But
- it could be different for ARM SoCs.
- - ARM options:
- CFG_SYS_EXCEPTION_VECTORS_HIGH
- Select high exception vectors of the ARM core, e.g., do not
- clear the V bit of the c1 register of CP15.
- COUNTER_FREQUENCY
- Generic timer clock source frequency.
- COUNTER_FREQUENCY_REAL
- Generic timer clock source frequency if the real clock is
- different from COUNTER_FREQUENCY, and can only be determined
- at run time.
- - Tegra SoC options:
- CONFIG_TEGRA_SUPPORT_NON_SECURE
- Support executing U-Boot in non-secure (NS) mode. Certain
- impossible actions will be skipped if the CPU is in NS mode,
- such as ARM architectural timer initialization.
- - Linux Kernel Interface:
- CONFIG_OF_LIBFDT
- New kernel versions are expecting firmware settings to be
- passed using flattened device trees (based on open firmware
- concepts).
- CONFIG_OF_LIBFDT
- * New libfdt-based support
- * Adds the "fdt" command
- * The bootm command automatically updates the fdt
- OF_TBCLK - The timebase frequency.
- boards with QUICC Engines require OF_QE to set UCC MAC
- addresses
- CONFIG_OF_IDE_FIXUP
- U-Boot can detect if an IDE device is present or not.
- If not, and this new config option is activated, U-Boot
- removes the ATA node from the DTS before booting Linux,
- so the Linux IDE driver does not probe the device and
- crash. This is needed for buggy hardware (uc101) where
- no pull down resistor is connected to the signal IDE5V_DD7.
- - vxWorks boot parameters:
- bootvx constructs a valid bootline using the following
- environments variables: bootdev, bootfile, ipaddr, netmask,
- serverip, gatewayip, hostname, othbootargs.
- It loads the vxWorks image pointed bootfile.
- Note: If a "bootargs" environment is defined, it will override
- the defaults discussed just above.
- - Cache Configuration for ARM:
- CFG_SYS_PL310_BASE - Physical base address of PL310
- controller register space
- - Serial Ports:
- CFG_PL011_CLOCK
- If you have Amba PrimeCell PL011 UARTs, set this variable to
- the clock speed of the UARTs.
- CFG_PL01x_PORTS
- If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
- define this to a list of base addresses for each (supported)
- port. See e.g. include/configs/versatile.h
- CONFIG_SERIAL_HW_FLOW_CONTROL
- Define this variable to enable hw flow control in serial driver.
- Current user of this option is drivers/serial/nsl16550.c driver
- - Removal of commands
- If no commands are needed to boot, you can disable
- CONFIG_CMDLINE to remove them. In this case, the command line
- will not be available, and when U-Boot wants to execute the
- boot command (on start-up) it will call board_run_command()
- instead. This can reduce image size significantly for very
- simple boot procedures.
- - Regular expression support:
- CONFIG_REGEX
- If this variable is defined, U-Boot is linked against
- the SLRE (Super Light Regular Expression) library,
- which adds regex support to some commands, as for
- example "env grep" and "setexpr".
- - Watchdog:
- CFG_SYS_WATCHDOG_FREQ
- Some platforms automatically call WATCHDOG_RESET()
- from the timer interrupt handler every
- CFG_SYS_WATCHDOG_FREQ interrupts. If not set by the
- board configuration file, a default of CONFIG_SYS_HZ/2
- (i.e. 500) is used. Setting CFG_SYS_WATCHDOG_FREQ
- to 0 disables calling WATCHDOG_RESET() from the timer
- interrupt.
- - GPIO Support:
- The CFG_SYS_I2C_PCA953X_WIDTH option specifies a list of
- chip-ngpio pairs that tell the PCA953X driver the number of
- pins supported by a particular chip.
- Note that if the GPIO device uses I2C, then the I2C interface
- must also be configured. See I2C Support, below.
- - I/O tracing:
- When CONFIG_IO_TRACE is selected, U-Boot intercepts all I/O
- accesses and can checksum them or write a list of them out
- to memory. See the 'iotrace' command for details. This is
- useful for testing device drivers since it can confirm that
- the driver behaves the same way before and after a code
- change. Currently this is supported on sandbox and arm. To
- add support for your architecture, add '#include <iotrace.h>'
- to the bottom of arch/<arch>/include/asm/io.h and test.
- Example output from the 'iotrace stats' command is below.
- Note that if the trace buffer is exhausted, the checksum will
- still continue to operate.
- iotrace is enabled
- Start: 10000000 (buffer start address)
- Size: 00010000 (buffer size)
- Offset: 00000120 (current buffer offset)
- Output: 10000120 (start + offset)
- Count: 00000018 (number of trace records)
- CRC32: 9526fb66 (CRC32 of all trace records)
- - Timestamp Support:
- When CONFIG_TIMESTAMP is selected, the timestamp
- (date and time) of an image is printed by image
- commands like bootm or iminfo. This option is
- automatically enabled when you select CONFIG_CMD_DATE .
- - Partition Labels (disklabels) Supported:
- Zero or more of the following:
- CONFIG_MAC_PARTITION Apple's MacOS partition table.
- CONFIG_ISO_PARTITION ISO partition table, used on CDROM etc.
- CONFIG_EFI_PARTITION GPT partition table, common when EFI is the
- bootloader. Note 2TB partition limit; see
- disk/part_efi.c
- CONFIG_SCSI) you must configure support for at
- least one non-MTD partition type as well.
- - NETWORK Support (PCI):
- CONFIG_E1000_SPI
- Utility code for direct access to the SPI bus on Intel 8257x.
- This does not do anything useful unless you set at least one
- of CONFIG_CMD_E1000 or CONFIG_E1000_SPI_GENERIC.
- CONFIG_NATSEMI
- Support for National dp83815 chips.
- CONFIG_NS8382X
- Support for National dp8382[01] gigabit chips.
- - NETWORK Support (other):
- CONFIG_CALXEDA_XGMAC
- Support for the Calxeda XGMAC device
- CONFIG_LAN91C96
- Support for SMSC's LAN91C96 chips.
- CONFIG_LAN91C96_USE_32_BIT
- Define this to enable 32 bit addressing
- CFG_SYS_DAVINCI_EMAC_PHY_COUNT
- Define this if you have more then 3 PHYs.
- CONFIG_FTGMAC100
- Support for Faraday's FTGMAC100 Gigabit SoC Ethernet
- CONFIG_FTGMAC100_EGIGA
- Define this to use GE link update with gigabit PHY.
- Define this if FTGMAC100 is connected to gigabit PHY.
- If your system has 10/100 PHY only, it might not occur
- wrong behavior. Because PHY usually return timeout or
- useless data when polling gigabit status and gigabit
- control registers. This behavior won't affect the
- correctnessof 10/100 link speed update.
- CONFIG_SH_ETHER
- Support for Renesas on-chip Ethernet controller
- CFG_SH_ETHER_USE_PORT
- Define the number of ports to be used
- CFG_SH_ETHER_PHY_ADDR
- Define the ETH PHY's address
- CFG_SH_ETHER_CACHE_WRITEBACK
- If this option is set, the driver enables cache flush.
- - TPM Support:
- CONFIG_TPM
- Support TPM devices.
- CONFIG_TPM_TIS_INFINEON
- Support for Infineon i2c bus TPM devices. Only one device
- per system is supported at this time.
- CONFIG_TPM_TIS_I2C_BURST_LIMITATION
- Define the burst count bytes upper limit
- CONFIG_TPM_ST33ZP24
- Support for STMicroelectronics TPM devices. Requires DM_TPM support.
- CONFIG_TPM_ST33ZP24_I2C
- Support for STMicroelectronics ST33ZP24 I2C devices.
- Requires TPM_ST33ZP24 and I2C.
- CONFIG_TPM_ST33ZP24_SPI
- Support for STMicroelectronics ST33ZP24 SPI devices.
- Requires TPM_ST33ZP24 and SPI.
- CONFIG_TPM_ATMEL_TWI
- Support for Atmel TWI TPM device. Requires I2C support.
- CONFIG_TPM_TIS_LPC
- Support for generic parallel port TPM devices. Only one device
- per system is supported at this time.
- CONFIG_TPM
- Define this to enable the TPM support library which provides
- functional interfaces to some TPM commands.
- Requires support for a TPM device.
- CONFIG_TPM_AUTH_SESSIONS
- Define this to enable authorized functions in the TPM library.
- Requires CONFIG_TPM and CONFIG_SHA1.
- - USB Support:
- At the moment only the UHCI host controller is
- supported (PIP405, MIP405); define
- CONFIG_USB_UHCI to enable it.
- define CONFIG_USB_KEYBOARD to enable the USB Keyboard
- and define CONFIG_USB_STORAGE to enable the USB
- storage devices.
- Note:
- Supported are USB Keyboards and USB Floppy drives
- (TEAC FD-05PUB).
- CONFIG_USB_DWC2_REG_ADDR the physical CPU address of the DWC2
- HW module registers.
- - USB Device:
- Define the below if you wish to use the USB console.
- Once firmware is rebuilt from a serial console issue the
- command "setenv stdin usbtty; setenv stdout usbtty" and
- attach your USB cable. The Unix command "dmesg" should print
- it has found a new device. The environment variable usbtty
- can be set to gserial or cdc_acm to enable your device to
- appear to a USB host as a Linux gserial device or a
- Common Device Class Abstract Control Model serial device.
- If you select usbtty = gserial you should be able to enumerate
- a Linux host by
- # modprobe usbserial vendor=0xVendorID product=0xProductID
- else if using cdc_acm, simply setting the environment
- variable usbtty to be cdc_acm should suffice. The following
- might be defined in YourBoardName.h
- If you have a USB-IF assigned VendorID then you may wish to
- define your own vendor specific values either in BoardName.h
- or directly in usbd_vendor_info.h. If you don't define
- CONFIG_USBD_MANUFACTURER, CONFIG_USBD_PRODUCT_NAME,
- CONFIG_USBD_VENDORID and CONFIG_USBD_PRODUCTID, then U-Boot
- should pretend to be a Linux device to it's target host.
- CONFIG_USBD_MANUFACTURER
- Define this string as the name of your company for
- - CONFIG_USBD_MANUFACTURER "my company"
- CONFIG_USBD_PRODUCT_NAME
- Define this string as the name of your product
- - CONFIG_USBD_PRODUCT_NAME "acme usb device"
- CONFIG_USBD_VENDORID
- Define this as your assigned Vendor ID from the USB
- Implementors Forum. This *must* be a genuine Vendor ID
- to avoid polluting the USB namespace.
- - CONFIG_USBD_VENDORID 0xFFFF
- CONFIG_USBD_PRODUCTID
- Define this as the unique Product ID
- for your device
- - CONFIG_USBD_PRODUCTID 0xFFFF
- - ULPI Layer Support:
- The ULPI (UTMI Low Pin (count) Interface) PHYs are supported via
- the generic ULPI layer. The generic layer accesses the ULPI PHY
- via the platform viewport, so you need both the genric layer and
- the viewport enabled. Currently only Chipidea/ARC based
- viewport is supported.
- To enable the ULPI layer support, define CONFIG_USB_ULPI and
- CONFIG_USB_ULPI_VIEWPORT in your board configuration file.
- If your ULPI phy needs a different reference clock than the
- standard 24 MHz then you have to define CFG_ULPI_REF_CLK to
- the appropriate value in Hz.
- - MMC Support:
- CONFIG_SH_MMCIF
- Support for Renesas on-chip MMCIF controller
- CONFIG_SH_MMCIF_ADDR
- Define the base address of MMCIF registers
- CONFIG_SH_MMCIF_CLK
- Define the clock frequency for MMCIF
- - USB Device Firmware Update (DFU) class support:
- CONFIG_DFU_OVER_USB
- This enables the USB portion of the DFU USB class
- CONFIG_DFU_NAND
- This enables support for exposing NAND devices via DFU.
- CONFIG_DFU_RAM
- This enables support for exposing RAM via DFU.
- Note: DFU spec refer to non-volatile memory usage, but
- allow usages beyond the scope of spec - here RAM usage,
- one that would help mostly the developer.
- CONFIG_SYS_DFU_DATA_BUF_SIZE
- Dfu transfer uses a buffer before writing data to the
- raw storage device. Make the size (in bytes) of this buffer
- configurable. The size of this buffer is also configurable
- through the "dfu_bufsiz" environment variable.
- CONFIG_SYS_DFU_MAX_FILE_SIZE
- When updating files rather than the raw storage device,
- we use a static buffer to copy the file into and then write
- the buffer once we've been given the whole file. Define
- this to the maximum filesize (in bytes) for the buffer.
- Default is 4 MiB if undefined.
- DFU_DEFAULT_POLL_TIMEOUT
- Poll timeout [ms], is the timeout a device can send to the
- host. The host must wait for this timeout before sending
- a subsequent DFU_GET_STATUS request to the device.
- DFU_MANIFEST_POLL_TIMEOUT
- Poll timeout [ms], which the device sends to the host when
- entering dfuMANIFEST state. Host waits this timeout, before
- sending again an USB request to the device.
- - Keyboard Support:
- See Kconfig help for available keyboard drivers.
- - MII/PHY support:
- CONFIG_PHY_CLOCK_FREQ (ppc4xx)
- The clock frequency of the MII bus
- CONFIG_PHY_CMD_DELAY (ppc4xx)
- Some PHY like Intel LXT971A need extra delay after
- command issued before MII status register can be read
- - BOOTP Recovery Mode:
- CONFIG_BOOTP_RANDOM_DELAY
- If you have many targets in a network that try to
- boot using BOOTP, you may want to avoid that all
- systems send out BOOTP requests at precisely the same
- moment (which would happen for instance at recovery
- from a power failure, when all systems will try to
- boot, thus flooding the BOOTP server. Defining
- CONFIG_BOOTP_RANDOM_DELAY causes a random delay to be
- inserted before sending out BOOTP requests. The
- following delays are inserted then:
- 1st BOOTP request: delay 0 ... 1 sec
- 2nd BOOTP request: delay 0 ... 2 sec
- 3rd BOOTP request: delay 0 ... 4 sec
- 4th and following
- BOOTP requests: delay 0 ... 8 sec
- CFG_BOOTP_ID_CACHE_SIZE
- BOOTP packets are uniquely identified using a 32-bit ID. The
- server will copy the ID from client requests to responses and
- U-Boot will use this to determine if it is the destination of
- an incoming response. Some servers will check that addresses
- aren't in use before handing them out (usually using an ARP
- ping) and therefore take up to a few hundred milliseconds to
- respond. Network congestion may also influence the time it
- takes for a response to make it back to the client. If that
- time is too long, U-Boot will retransmit requests. In order
- to allow earlier responses to still be accepted after these
- retransmissions, U-Boot's BOOTP client keeps a small cache of
- IDs. The CFG_BOOTP_ID_CACHE_SIZE controls the size of this
- cache. The default is to keep IDs for up to four outstanding
- requests. Increasing this will allow U-Boot to accept offers
- from a BOOTP client in networks with unusually high latency.
- - DHCP Advanced Options:
- - Link-local IP address negotiation:
- Negotiate with other link-local clients on the local network
- for an address that doesn't require explicit configuration.
- This is especially useful if a DHCP server cannot be guaranteed
- to exist in all environments that the device must operate.
- See doc/README.link-local for more information.
- - MAC address from environment variables
- FDT_SEQ_MACADDR_FROM_ENV
- Fix-up device tree with MAC addresses fetched sequentially from
- environment variables. This config work on assumption that
- non-usable ethernet node of device-tree are either not present
- or their status has been marked as "disabled".
- - CDP Options:
- CONFIG_CDP_DEVICE_ID
- The device id used in CDP trigger frames.
- CONFIG_CDP_DEVICE_ID_PREFIX
- A two character string which is prefixed to the MAC address
- of the device.
- CONFIG_CDP_PORT_ID
- A printf format string which contains the ascii name of
- the port. Normally is set to "eth%d" which sets
- eth0 for the first Ethernet, eth1 for the second etc.
- CONFIG_CDP_CAPABILITIES
- A 32bit integer which indicates the device capabilities;
- 0x00000010 for a normal host which does not forwards.
- CONFIG_CDP_VERSION
- An ascii string containing the version of the software.
- CONFIG_CDP_PLATFORM
- An ascii string containing the name of the platform.
- CONFIG_CDP_TRIGGER
- A 32bit integer sent on the trigger.
- CONFIG_CDP_POWER_CONSUMPTION
- A 16bit integer containing the power consumption of the
- device in .1 of milliwatts.
- CONFIG_CDP_APPLIANCE_VLAN_TYPE
- A byte containing the id of the VLAN.
- - Status LED: CONFIG_LED_STATUS
- Several configurations allow to display the current
- status using a LED. For instance, the LED will blink
- fast while running U-Boot code, stop blinking as
- soon as a reply to a BOOTP request was received, and
- start blinking slow once the Linux kernel is running
- (supported by a status LED driver in the Linux
- kernel). Defining CONFIG_LED_STATUS enables this
- feature in U-Boot.
- Additional options:
- CONFIG_LED_STATUS_GPIO
- The status LED can be connected to a GPIO pin.
- In such cases, the gpio_led driver can be used as a
- status LED backend implementation. Define CONFIG_LED_STATUS_GPIO
- to include the gpio_led driver in the U-Boot binary.
- CFG_GPIO_LED_INVERTED_TABLE
- Some GPIO connected LEDs may have inverted polarity in which
- case the GPIO high value corresponds to LED off state and
- GPIO low value corresponds to LED on state.
- In such cases CFG_GPIO_LED_INVERTED_TABLE may be defined
- with a list of GPIO LEDs that have inverted polarity.
- - I2C Support:
- CFG_SYS_NUM_I2C_BUSES
- Hold the number of i2c buses you want to use.
- CFG_SYS_I2C_DIRECT_BUS
- define this, if you don't use i2c muxes on your hardware.
- if CFG_SYS_I2C_MAX_HOPS is not defined or == 0 you can
- omit this define.
- CFG_SYS_I2C_MAX_HOPS
- define how many muxes are maximal consecutively connected
- on one i2c bus. If you not use i2c muxes, omit this
- define.
- CFG_SYS_I2C_BUSES
- hold a list of buses you want to use, only used if
- CFG_SYS_I2C_DIRECT_BUS is not defined, for example
- a board with CFG_SYS_I2C_MAX_HOPS = 1 and
- CFG_SYS_NUM_I2C_BUSES = 9:
- CFG_SYS_I2C_BUSES {{0, {I2C_NULL_HOP}}, \
- {0, {{I2C_MUX_PCA9547, 0x70, 1}}}, \
- {0, {{I2C_MUX_PCA9547, 0x70, 2}}}, \
- {0, {{I2C_MUX_PCA9547, 0x70, 3}}}, \
- {0, {{I2C_MUX_PCA9547, 0x70, 4}}}, \
- {0, {{I2C_MUX_PCA9547, 0x70, 5}}}, \
- {1, {I2C_NULL_HOP}}, \
- {1, {{I2C_MUX_PCA9544, 0x72, 1}}}, \
- {1, {{I2C_MUX_PCA9544, 0x72, 2}}}, \
- }
- which defines
- bus 0 on adapter 0 without a mux
- bus 1 on adapter 0 with a PCA9547 on address 0x70 port 1
- bus 2 on adapter 0 with a PCA9547 on address 0x70 port 2
- bus 3 on adapter 0 with a PCA9547 on address 0x70 port 3
- bus 4 on adapter 0 with a PCA9547 on address 0x70 port 4
- bus 5 on adapter 0 with a PCA9547 on address 0x70 port 5
- bus 6 on adapter 1 without a mux
- bus 7 on adapter 1 with a PCA9544 on address 0x72 port 1
- bus 8 on adapter 1 with a PCA9544 on address 0x72 port 2
- If you do not have i2c muxes on your board, omit this define.
- - Legacy I2C Support:
- If you use the software i2c interface (CONFIG_SYS_I2C_SOFT)
- then the following macros need to be defined (examples are
- from include/configs/lwmon.h):
- I2C_INIT
- (Optional). Any commands necessary to enable the I2C
- controller or configure ports.
- eg: #define I2C_INIT (immr->im_cpm.cp_pbdir |= PB_SCL)
- I2C_ACTIVE
- The code necessary to make the I2C data line active
- (driven). If the data line is open collector, this
- define can be null.
- eg: #define I2C_ACTIVE (immr->im_cpm.cp_pbdir |= PB_SDA)
- I2C_TRISTATE
- The code necessary to make the I2C data line tri-stated
- (inactive). If the data line is open collector, this
- define can be null.
- eg: #define I2C_TRISTATE (immr->im_cpm.cp_pbdir &= ~PB_SDA)
- I2C_READ
- Code that returns true if the I2C data line is high,
- false if it is low.
- eg: #define I2C_READ ((immr->im_cpm.cp_pbdat & PB_SDA) != 0)
- I2C_SDA(bit)
- If <bit> is true, sets the I2C data line high. If it
- is false, it clears it (low).
- eg: #define I2C_SDA(bit) \
- if(bit) immr->im_cpm.cp_pbdat |= PB_SDA; \
- else immr->im_cpm.cp_pbdat &= ~PB_SDA
- I2C_SCL(bit)
- If <bit> is true, sets the I2C clock line high. If it
- is false, it clears it (low).
- eg: #define I2C_SCL(bit) \
- if(bit) immr->im_cpm.cp_pbdat |= PB_SCL; \
- else immr->im_cpm.cp_pbdat &= ~PB_SCL
- I2C_DELAY
- This delay is invoked four times per clock cycle so this
- controls the rate of data transfer. The data rate thus
- is 1 / (I2C_DELAY * 4). Often defined to be something
- like:
- #define I2C_DELAY udelay(2)
- CONFIG_SOFT_I2C_GPIO_SCL / CONFIG_SOFT_I2C_GPIO_SDA
- If your arch supports the generic GPIO framework (asm/gpio.h),
- then you may alternatively define the two GPIOs that are to be
- used as SCL / SDA. Any of the previous I2C_xxx macros will
- have GPIO-based defaults assigned to them as appropriate.
- You should define these to the GPIO value as given directly to
- the generic GPIO functions.
- CFG_I2C_MULTI_BUS
- This option allows the use of multiple I2C buses, each of which
- must have a controller. At any point in time, only one bus is
- active. To switch to a different bus, use the 'i2c dev' command.
- Note that bus numbering is zero-based.
- CFG_SYS_I2C_NOPROBES
- This option specifies a list of I2C devices that will be skipped
- when the 'i2c probe' command is issued.
- e.g.
- #define CFG_SYS_I2C_NOPROBES {0x50,0x68}
- will skip addresses 0x50 and 0x68 on a board with one I2C bus
- CFG_SYS_RTC_BUS_NUM
- If defined, then this indicates the I2C bus number for the RTC.
- If not defined, then U-Boot assumes that RTC is on I2C bus 0.
- CONFIG_SOFT_I2C_READ_REPEATED_START
- defining this will force the i2c_read() function in
- the soft_i2c driver to perform an I2C repeated start
- between writing the address pointer and reading the
- data. If this define is omitted the default behaviour
- of doing a stop-start sequence will be used. Most I2C
- devices can use either method, but some require one or
- the other.
- - SPI Support: CONFIG_SPI
- Enables SPI driver (so far only tested with
- SPI EEPROM, also an instance works with Crystal A/D and
- D/As on the SACSng board)
- CFG_SYS_SPI_MXC_WAIT
- Timeout for waiting until spi transfer completed.
- default: (CONFIG_SYS_HZ/100) /* 10 ms */
- - FPGA Support: CONFIG_FPGA
- Enables FPGA subsystem.
- CONFIG_FPGA_<vendor>
- Enables support for specific chip vendors.
- (ALTERA, XILINX)
- CONFIG_FPGA_<family>
- Enables support for FPGA family.
- (SPARTAN2, SPARTAN3, VIRTEX2, CYCLONE2, ACEX1K, ACEX)
- CONFIG_SYS_FPGA_CHECK_BUSY
- Enable checks on FPGA configuration interface busy
- status by the configuration function. This option
- will require a board or device specific function to
- be written.
- CFG_FPGA_DELAY
- If defined, a function that provides delays in the FPGA
- configuration driver.
- CFG_SYS_FPGA_CHECK_ERROR
- Check for configuration errors during FPGA bitfile
- loading. For example, abort during Virtex II
- configuration if the INIT_B line goes low (which
- indicated a CRC error).
- CFG_SYS_FPGA_WAIT_INIT
- Maximum time to wait for the INIT_B line to de-assert
- after PROB_B has been de-asserted during a Virtex II
- FPGA configuration sequence. The default time is 500
- ms.
- CFG_SYS_FPGA_WAIT_BUSY
- Maximum time to wait for BUSY to de-assert during
- Virtex II FPGA configuration. The default is 5 ms.
- CFG_SYS_FPGA_WAIT_CONFIG
- Time to wait after FPGA configuration. The default is
- 200 ms.
- - Vendor Parameter Protection:
- U-Boot considers the values of the environment
- variables "serial#" (Board Serial Number) and
- "ethaddr" (Ethernet Address) to be parameters that
- are set once by the board vendor / manufacturer, and
- protects these variables from casual modification by
- the user. Once set, these variables are read-only,
- and write or delete attempts are rejected. You can
- change this behaviour:
- If CONFIG_ENV_OVERWRITE is #defined in your config
- file, the write protection for vendor parameters is
- completely disabled. Anybody can change or delete
- these parameters.
- The same can be accomplished in a more flexible way
- for any variable by configuring the type of access
- to allow for those variables in the ".flags" variable
- or define CFG_ENV_FLAGS_LIST_STATIC.
- - Protected RAM:
- CFG_PRAM
- Define this variable to enable the reservation of
- "protected RAM", i. e. RAM which is not overwritten
- by U-Boot. Define CFG_PRAM to hold the number of
- kB you want to reserve for pRAM. You can overwrite
- this default value by defining an environment
- variable "pram" to the number of kB you want to
- reserve. Note that the board info structure will
- still show the full amount of RAM. If pRAM is
- reserved, a new environment variable "mem" will
- automatically be defined to hold the amount of
- remaining RAM in a form that can be passed as boot
- argument to Linux, for instance like that:
- setenv bootargs ... mem=\${mem}
- saveenv
- This way you can tell Linux not to use this memory,
- either, which results in a memory region that will
- not be affected by reboots.
- *WARNING* If your board configuration uses automatic
- detection of the RAM size, you must make sure that
- this memory test is non-destructive. So far, the
- following board configurations are known to be
- "pRAM-clean":
- IVMS8, IVML24, SPD8xx,
- HERMES, IP860, RPXlite, LWMON,
- FLAGADM
- - Error Recovery:
- Note:
- In the current implementation, the local variables
- space and global environment variables space are
- separated. Local variables are those you define by
- simply typing `name=value'. To access a local
- variable later on, you have write `$name' or
- `${name}'; to execute the contents of a variable
- directly type `$name' at the command prompt.
- Global environment variables are those you use
- setenv/printenv to work with. To run a command stored
- in such a variable, you need to use the run command,
- and you must not use the '$' sign to access them.
- To store commands and special characters in a
- variable, please use double quotation marks
- surrounding the whole text of the variable, instead
- of the backslashes before semicolons and special
- symbols.
- - Default Environment:
- CFG_EXTRA_ENV_SETTINGS
- Define this to contain any number of null terminated
- strings (variable = value pairs) that will be part of
- the default environment compiled into the boot image.
- For example, place something like this in your
- board's config file:
- #define CFG_EXTRA_ENV_SETTINGS \
- "myvar1=value1\0" \
- "myvar2=value2\0"
- Warning: This method is based on knowledge about the
- internal format how the environment is stored by the
- U-Boot code. This is NOT an official, exported
- interface! Although it is unlikely that this format
- will change soon, there is no guarantee either.
- You better know what you are doing here.
- Note: overly (ab)use of the default environment is
- discouraged. Make sure to check other ways to preset
- the environment like the "source" command or the
- boot command first.
- CONFIG_DELAY_ENVIRONMENT
- Normally the environment is loaded when the board is
- initialised so that it is available to U-Boot. This inhibits
- that so that the environment is not available until
- explicitly loaded later by U-Boot code. With CONFIG_OF_CONTROL
- this is instead controlled by the value of
- /config/load-environment.
- - Automatic software updates via TFTP server
- CONFIG_UPDATE_TFTP
- CONFIG_UPDATE_TFTP_CNT_MAX
- CONFIG_UPDATE_TFTP_MSEC_MAX
- These options enable and control the auto-update feature;
- for a more detailed description refer to doc/README.update.
- - MTD Support (mtdparts command, UBI support)
- CONFIG_MTD_UBI_WL_THRESHOLD
- This parameter defines the maximum difference between the highest
- erase counter value and the lowest erase counter value of eraseblocks
- of UBI devices. When this threshold is exceeded, UBI starts performing
- wear leveling by means of moving data from eraseblock with low erase
- counter to eraseblocks with high erase counter.
- The default value should be OK for SLC NAND flashes, NOR flashes and
- other flashes which have eraseblock life-cycle 100000 or more.
- However, in case of MLC NAND flashes which typically have eraseblock
- life-cycle less than 10000, the threshold should be lessened (e.g.,
- to 128 or 256, although it does not have to be power of 2).
- default: 4096
- CONFIG_MTD_UBI_BEB_LIMIT
- This option specifies the maximum bad physical eraseblocks UBI
- expects on the MTD device (per 1024 eraseblocks). If the
- underlying flash does not admit of bad eraseblocks (e.g. NOR
- flash), this value is ignored.
- NAND datasheets often specify the minimum and maximum NVM
- (Number of Valid Blocks) for the flashes' endurance lifetime.
- The maximum expected bad eraseblocks per 1024 eraseblocks
- then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
- which gives 20 for most NANDs (MaxNVB is basically the total
- count of eraseblocks on the chip).
- To put it differently, if this value is 20, UBI will try to
- reserve about 1.9% of physical eraseblocks for bad blocks
- handling. And that will be 1.9% of eraseblocks on the entire
- NAND chip, not just the MTD partition UBI attaches. This means
- that if you have, say, a NAND flash chip admits maximum 40 bad
- eraseblocks, and it is split on two MTD partitions of the same
- size, UBI will reserve 40 eraseblocks when attaching a
- partition.
- default: 20
- CONFIG_MTD_UBI_FASTMAP
- Fastmap is a mechanism which allows attaching an UBI device
- in nearly constant time. Instead of scanning the whole MTD device it
- only has to locate a checkpoint (called fastmap) on the device.
- The on-flash fastmap contains all information needed to attach
- the device. Using fastmap makes only sense on large devices where
- attaching by scanning takes long. UBI will not automatically install
- a fastmap on old images, but you can set the UBI parameter
- CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
- that fastmap-enabled images are still usable with UBI implementations
- without fastmap support. On typical flash devices the whole fastmap
- fits into one PEB. UBI will reserve PEBs to hold two fastmaps.
- CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
- Set this parameter to enable fastmap automatically on images
- without a fastmap.
- default: 0
- CONFIG_MTD_UBI_FM_DEBUG
- Enable UBI fastmap debug
- default: 0
- - SPL framework
- CONFIG_SPL
- Enable building of SPL globally.
- CONFIG_SPL_PANIC_ON_RAW_IMAGE
- When defined, SPL will panic() if the image it has
- loaded does not have a signature.
- Defining this is useful when code which loads images
- in SPL cannot guarantee that absolutely all read errors
- will be caught.
- An example is the LPC32XX MLC NAND driver, which will
- consider that a completely unreadable NAND block is bad,
- and thus should be skipped silently.
- CONFIG_SPL_DISPLAY_PRINT
- For ARM, enable an optional function to print more information
- about the running system.
- CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
- Set this for NAND SPL on PPC mpc83xx targets, so that
- start.S waits for the rest of the SPL to load before
- continuing (the hardware starts execution after just
- loading the first page rather than the full 4K).
- CONFIG_SPL_UBI
- Support for a lightweight UBI (fastmap) scanner and
- loader
- CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
- CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
- CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
- CFG_SYS_NAND_ECCPOS, CFG_SYS_NAND_ECCSIZE,
- CFG_SYS_NAND_ECCBYTES
- Defines the size and behavior of the NAND that SPL uses
- to read U-Boot
- CFG_SYS_NAND_U_BOOT_DST
- Location in memory to load U-Boot to
- CFG_SYS_NAND_U_BOOT_SIZE
- Size of image to load
- CFG_SYS_NAND_U_BOOT_START
- Entry point in loaded image to jump to
- CONFIG_SPL_RAM_DEVICE
- Support for running image already present in ram, in SPL binary
- CONFIG_SPL_FIT_PRINT
- Printing information about a FIT image adds quite a bit of
- code to SPL. So this is normally disabled in SPL. Use this
- option to re-enable it. This will affect the output of the
- bootm command when booting a FIT image.
- - Interrupt support (PPC):
- There are common interrupt_init() and timer_interrupt()
- for all PPC archs. interrupt_init() calls interrupt_init_cpu()
- for CPU specific initialization. interrupt_init_cpu()
- should set decrementer_count to appropriate value. If
- CPU resets decrementer automatically after interrupt
- (ppc4xx) it should set decrementer_count to zero.
- timer_interrupt() calls timer_interrupt_cpu() for CPU
- specific handling. If board has watchdog / status_led
- / other_activity_monitor it works automatically from
- general timer_interrupt().
- Board initialization settings:
- ------------------------------
- During Initialization u-boot calls a number of board specific functions
- to allow the preparation of board specific prerequisites, e.g. pin setup
- before drivers are initialized. To enable these callbacks the
- following configuration macros have to be defined. Currently this is
- architecture specific, so please check arch/your_architecture/lib/board.c
- typically in board_init_f() and board_init_r().
- - CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
- - CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
- - CONFIG_BOARD_LATE_INIT: Call board_late_init()
- Configuration Settings:
- -----------------------
- - MEM_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
- Optionally it can be defined to support 64-bit memory commands.
- - CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
- undefine this when you're short of memory.
- - CFG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
- width of the commands listed in the 'help' command output.
- - CONFIG_SYS_PROMPT: This is what U-Boot prints on the console to
- prompt for user input.
- - CFG_SYS_BAUDRATE_TABLE:
- List of legal baudrate settings for this board.
- - CFG_SYS_MEM_RESERVE_SECURE
- Only implemented for ARMv8 for now.
- If defined, the size of CFG_SYS_MEM_RESERVE_SECURE memory
- is substracted from total RAM and won't be reported to OS.
- This memory can be used as secure memory. A variable
- gd->arch.secure_ram is used to track the location. In systems
- the RAM base is not zero, or RAM is divided into banks,
- this variable needs to be recalcuated to get the address.
- - CFG_SYS_SDRAM_BASE:
- Physical start address of SDRAM. _Must_ be 0 here.
- - CFG_SYS_FLASH_BASE:
- Physical start address of Flash memory.
- - CONFIG_SYS_MALLOC_LEN:
- Size of DRAM reserved for malloc() use.
- - CONFIG_SYS_MALLOC_F_LEN
- Size of the malloc() pool for use before relocation. If
- this is defined, then a very simple malloc() implementation
- will become available before relocation. The address is just
- below the global data, and the stack is moved down to make
- space.
- This feature allocates regions with increasing addresses
- within the region. calloc() is supported, but realloc()
- is not available. free() is supported but does nothing.
- The memory will be freed (or in fact just forgotten) when
- U-Boot relocates itself.
- - CONFIG_SYS_MALLOC_SIMPLE
- Provides a simple and small malloc() and calloc() for those
- boards which do not use the full malloc in SPL (which is
- enabled with CONFIG_SYS_SPL_MALLOC).
- - CFG_SYS_BOOTMAPSZ:
- Maximum size of memory mapped by the startup code of
- the Linux kernel; all data that must be processed by
- the Linux kernel (bd_info, boot arguments, FDT blob if
- used) must be put below this limit, unless "bootm_low"
- environment variable is defined and non-zero. In such case
- all data for the Linux kernel must be between "bootm_low"
- and "bootm_low" + CFG_SYS_BOOTMAPSZ. The environment
- variable "bootm_mapsize" will override the value of
- CFG_SYS_BOOTMAPSZ. If CFG_SYS_BOOTMAPSZ is undefined,
- then the value in "bootm_size" will be used instead.
- - CONFIG_SYS_BOOT_GET_CMDLINE:
- Enables allocating and saving kernel cmdline in space between
- "bootm_low" and "bootm_low" + BOOTMAPSZ.
- - CONFIG_SYS_BOOT_GET_KBD:
- Enables allocating and saving a kernel copy of the bd_info in
- space between "bootm_low" and "bootm_low" + BOOTMAPSZ.
- - CONFIG_SYS_FLASH_PROTECTION
- If defined, hardware flash sectors protection is used
- instead of U-Boot software protection.
- - CONFIG_SYS_FLASH_CFI:
- Define if the flash driver uses extra elements in the
- common flash structure for storing flash geometry.
- - CONFIG_FLASH_CFI_DRIVER
- This option also enables the building of the cfi_flash driver
- in the drivers directory
- - CONFIG_FLASH_CFI_MTD
- This option enables the building of the cfi_mtd driver
- in the drivers directory. The driver exports CFI flash
- to the MTD layer.
- - CONFIG_SYS_FLASH_USE_BUFFER_WRITE
- Use buffered writes to flash.
- - CONFIG_ENV_FLAGS_LIST_DEFAULT
- - CFG_ENV_FLAGS_LIST_STATIC
- Enable validation of the values given to environment variables when
- calling env set. Variables can be restricted to only decimal,
- hexadecimal, or boolean. If CONFIG_CMD_NET is also defined,
- the variables can also be restricted to IP address or MAC address.
- The format of the list is:
- type_attribute = [s|d|x|b|i|m]
- access_attribute = [a|r|o|c]
- attributes = type_attribute[access_attribute]
- entry = variable_name[:attributes]
- list = entry[,list]
- The type attributes are:
- s - String (default)
- d - Decimal
- x - Hexadecimal
- b - Boolean ([1yYtT|0nNfF])
- i - IP address
- m - MAC address
- The access attributes are:
- a - Any (default)
- r - Read-only
- o - Write-once
- c - Change-default
- - CONFIG_ENV_FLAGS_LIST_DEFAULT
- Define this to a list (string) to define the ".flags"
- environment variable in the default or embedded environment.
- - CFG_ENV_FLAGS_LIST_STATIC
- Define this to a list (string) to define validation that
- should be done if an entry is not found in the ".flags"
- environment variable. To override a setting in the static
- list, simply add an entry for the same variable name to the
- ".flags" variable.
- If CONFIG_REGEX is defined, the variable_name above is evaluated as a
- regular expression. This allows multiple variables to define the same
- flags without explicitly listing them for each variable.
- The following definitions that deal with the placement and management
- of environment data (variable area); in general, we support the
- following configurations:
- BE CAREFUL! The first access to the environment happens quite early
- in U-Boot initialization (when we try to get the setting of for the
- console baudrate). You *MUST* have mapped your NVRAM area then, or
- U-Boot will hang.
- Please note that even with NVRAM we still use a copy of the
- environment in RAM: we could work on NVRAM directly, but we want to
- keep settings there always unmodified except somebody uses "saveenv"
- to save the current settings.
- BE CAREFUL! For some special cases, the local device can not use
- "saveenv" command. For example, the local device will get the
- environment stored in a remote NOR flash by SRIO or PCIE link,
- but it can not erase, write this NOR flash by SRIO or PCIE interface.
- - CONFIG_NAND_ENV_DST
- Defines address in RAM to which the nand_spl code should copy the
- environment. If redundant environment is used, it will be copied to
- CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.
- Please note that the environment is read-only until the monitor
- has been relocated to RAM and a RAM copy of the environment has been
- created; also, when using EEPROM you will have to use env_get_f()
- until then to read environment variables.
- The environment is protected by a CRC32 checksum. Before the monitor
- is relocated into RAM, as a result of a bad CRC you will be working
- with the compiled-in default environment - *silently*!!! [This is
- necessary, because the first environment variable we need is the
- "baudrate" setting for the console - if we have a bad CRC, we don't
- have any device yet where we could complain.]
- Note: once the monitor has been relocated, then it will complain if
- the default environment is used; a new CRC is computed as soon as you
- use the "saveenv" command to store a valid environment.
- - CONFIG_SYS_FAULT_MII_ADDR:
- MII address of the PHY to check for the Ethernet link state.
- - CONFIG_DISPLAY_BOARDINFO
- Display information about the board that U-Boot is running on
- when U-Boot starts up. The board function checkboard() is called
- to do this.
- - CONFIG_DISPLAY_BOARDINFO_LATE
- Similar to the previous option, but display this information
- later, once stdio is running and output goes to the LCD, if
- present.
- Low Level (hardware related) configuration options:
- ---------------------------------------------------
- - CONFIG_SYS_CACHELINE_SIZE:
- Cache Line Size of the CPU.
- - CONFIG_SYS_CCSRBAR_DEFAULT:
- Default (power-on reset) physical address of CCSR on Freescale
- PowerPC SOCs.
- - CFG_SYS_CCSRBAR:
- Virtual address of CCSR. On a 32-bit build, this is typically
- the same value as CONFIG_SYS_CCSRBAR_DEFAULT.
- - CFG_SYS_CCSRBAR_PHYS:
- Physical address of CCSR. CCSR can be relocated to a new
- physical address, if desired. In this case, this macro should
- be set to that address. Otherwise, it should be set to the
- same value as CONFIG_SYS_CCSRBAR_DEFAULT. For example, CCSR
- is typically relocated on 36-bit builds. It is recommended
- that this macro be defined via the _HIGH and _LOW macros:
- #define CFG_SYS_CCSRBAR_PHYS ((CFG_SYS_CCSRBAR_PHYS_HIGH
- * 1ull) << 32 | CFG_SYS_CCSRBAR_PHYS_LOW)
- - CFG_SYS_CCSRBAR_PHYS_HIGH:
- Bits 33-36 of CFG_SYS_CCSRBAR_PHYS. This value is typically
- either 0 (32-bit build) or 0xF (36-bit build). This macro is
- used in assembly code, so it must not contain typecasts or
- integer size suffixes (e.g. "ULL").
- - CFG_SYS_CCSRBAR_PHYS_LOW:
- Lower 32-bits of CFG_SYS_CCSRBAR_PHYS. This macro is
- used in assembly code, so it must not contain typecasts or
- integer size suffixes (e.g. "ULL").
- - CONFIG_SYS_IMMR: Physical address of the Internal Memory.
- DO NOT CHANGE unless you know exactly what you're
- doing! (11-4) [MPC8xx systems only]
- - CFG_SYS_INIT_RAM_ADDR:
- Start address of memory area that can be used for
- initial data and stack; please note that this must be
- writable memory that is working WITHOUT special
- initialization, i. e. you CANNOT use normal RAM which
- will become available only after programming the
- memory controller and running certain initialization
- sequences.
- U-Boot uses the following memory types:
- - MPC8xx: IMMR (internal memory of the CPU)
- - CONFIG_SYS_SCCR: System Clock and reset Control Register (15-27)
- - CONFIG_SYS_OR_TIMING_SDRAM:
- SDRAM timing
- - CONFIG_SYS_SRIOn_MEM_VIRT:
- Virtual Address of SRIO port 'n' memory region
- - CONFIG_SYS_SRIOn_MEM_PHYxS:
- Physical Address of SRIO port 'n' memory region
- - CONFIG_SYS_SRIOn_MEM_SIZE:
- Size of SRIO port 'n' memory region
- - CONFIG_SYS_NAND_BUSWIDTH_16BIT
- Defined to tell the NAND controller that the NAND chip is using
- a 16 bit bus.
- Not all NAND drivers use this symbol.
- Example of drivers that use it:
- - drivers/mtd/nand/raw/ndfc.c
- - drivers/mtd/nand/raw/mxc_nand.c
- - CONFIG_SYS_NDFC_EBC0_CFG
- Sets the EBC0_CFG register for the NDFC. If not defined
- a default value will be used.
- - CONFIG_SYS_SPD_BUS_NUM
- If SPD EEPROM is on an I2C bus other than the first
- one, specify here. Note that the value must resolve
- to something your driver can deal with.
- - CONFIG_FSL_DDR_INTERACTIVE
- Enable interactive DDR debugging. See doc/README.fsl-ddr.
- - CONFIG_FSL_DDR_SYNC_REFRESH
- Enable sync of refresh for multiple controllers.
- - CONFIG_FSL_DDR_BIST
- Enable built-in memory test for Freescale DDR controllers.
- - CONFIG_RMII
- Enable RMII mode for all FECs.
- Note that this is a global option, we can't
- have one FEC in standard MII mode and another in RMII mode.
- - CONFIG_CRC32_VERIFY
- Add a verify option to the crc32 command.
- The syntax is:
- => crc32 -v <address> <count> <crc32>
- Where address/count indicate a memory area
- and crc32 is the correct crc32 which the
- area should have.
- - CONFIG_LOOPW
- Add the "loopw" memory command. This only takes effect if
- the memory commands are activated globally (CONFIG_CMD_MEMORY).
- - CONFIG_CMD_MX_CYCLIC
- Add the "mdc" and "mwc" memory commands. These are cyclic
- "md/mw" commands.
- Examples:
- => mdc.b 10 4 500
- This command will print 4 bytes (10,11,12,13) each 500 ms.
- => mwc.l 100 12345678 10
- This command will write 12345678 to address 100 all 10 ms.
- This only takes effect if the memory commands are activated
- globally (CONFIG_CMD_MEMORY).
- - CONFIG_SPL_BUILD
- Set when the currently-running compilation is for an artifact
- that will end up in the SPL (as opposed to the TPL or U-Boot
- proper). Code that needs stage-specific behavior should check
- this.
- - CONFIG_TPL_BUILD
- Set when the currently-running compilation is for an artifact
- that will end up in the TPL (as opposed to the SPL or U-Boot
- proper). Code that needs stage-specific behavior should check
- this.
- - CONFIG_ARCH_MAP_SYSMEM
- Generally U-Boot (and in particular the md command) uses
- effective address. It is therefore not necessary to regard
- U-Boot address as virtual addresses that need to be translated
- to physical addresses. However, sandbox requires this, since
- it maintains its own little RAM buffer which contains all
- addressable memory. This option causes some memory accesses
- to be mapped through map_sysmem() / unmap_sysmem().
- - CONFIG_X86_RESET_VECTOR
- If defined, the x86 reset vector code is included. This is not
- needed when U-Boot is running from Coreboot.
- Freescale QE/FMAN Firmware Support:
- -----------------------------------
- The Freescale QUICCEngine (QE) and Frame Manager (FMAN) both support the
- loading of "firmware", which is encoded in the QE firmware binary format.
- This firmware often needs to be loaded during U-Boot booting, so macros
- are used to identify the storage device (NOR flash, SPI, etc) and the address
- within that device.
- - CONFIG_SYS_FMAN_FW_ADDR
- The address in the storage device where the FMAN microcode is located. The
- meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
- is also specified.
- - CONFIG_SYS_QE_FW_ADDR
- The address in the storage device where the QE microcode is located. The
- meaning of this address depends on which CONFIG_SYS_QE_FMAN_FW_IN_xxx macro
- is also specified.
- - CONFIG_SYS_QE_FMAN_FW_LENGTH
- The maximum possible size of the firmware. The firmware binary format
- has a field that specifies the actual size of the firmware, but it
- might not be possible to read any part of the firmware unless some
- local storage is allocated to hold the entire firmware first.
- - CONFIG_SYS_QE_FMAN_FW_IN_NOR
- Specifies that QE/FMAN firmware is located in NOR flash, mapped as
- normal addressable memory via the LBC. CONFIG_SYS_FMAN_FW_ADDR is the
- virtual address in NOR flash.
- - CONFIG_SYS_QE_FMAN_FW_IN_NAND
- Specifies that QE/FMAN firmware is located in NAND flash.
- CONFIG_SYS_FMAN_FW_ADDR is the offset within NAND flash.
- - CONFIG_SYS_QE_FMAN_FW_IN_MMC
- Specifies that QE/FMAN firmware is located on the primary SD/MMC
- device. CONFIG_SYS_FMAN_FW_ADDR is the byte offset on that device.
- - CONFIG_SYS_QE_FMAN_FW_IN_REMOTE
- Specifies that QE/FMAN firmware is located in the remote (master)
- memory space. CONFIG_SYS_FMAN_FW_ADDR is a virtual address which
- can be mapped from slave TLB->slave LAW->slave SRIO or PCIE outbound
- window->master inbound window->master LAW->the ucode address in
- master's memory space.
- Freescale Layerscape Management Complex Firmware Support:
- ---------------------------------------------------------
- The Freescale Layerscape Management Complex (MC) supports the loading of
- "firmware".
- This firmware often needs to be loaded during U-Boot booting, so macros
- are used to identify the storage device (NOR flash, SPI, etc) and the address
- within that device.
- - CONFIG_FSL_MC_ENET
- Enable the MC driver for Layerscape SoCs.
- Freescale Layerscape Debug Server Support:
- -------------------------------------------
- The Freescale Layerscape Debug Server Support supports the loading of
- "Debug Server firmware" and triggering SP boot-rom.
- This firmware often needs to be loaded during U-Boot booting.
- - CONFIG_SYS_MC_RSV_MEM_ALIGN
- Define alignment of reserved memory MC requires
- Building the Software:
- ======================
- Building U-Boot has been tested in several native build environments
- and in many different cross environments. Of course we cannot support
- all possibly existing versions of cross development tools in all
- (potentially obsolete) versions. In case of tool chain problems we
- recommend to use the ELDK (see https://www.denx.de/wiki/DULG/ELDK)
- which is extensively used to build and test U-Boot.
- If you are not using a native environment, it is assumed that you
- have GNU cross compiling tools available in your path. In this case,
- you must set the environment variable CROSS_COMPILE in your shell.
- Note that no changes to the Makefile or any other source files are
- necessary. For example using the ELDK on a 4xx CPU, please enter:
- $ CROSS_COMPILE=ppc_4xx-
- $ export CROSS_COMPILE
- U-Boot is intended to be simple to build. After installing the
- sources you must configure U-Boot for one specific board type. This
- is done by typing:
- make NAME_defconfig
- where "NAME_defconfig" is the name of one of the existing configu-
- rations; see configs/*_defconfig for supported names.
- Note: for some boards special configuration names may exist; check if
- additional information is available from the board vendor; for
- instance, the TQM823L systems are available without (standard)
- or with LCD support. You can select such additional "features"
- when choosing the configuration, i. e.
- make TQM823L_defconfig
- - will configure for a plain TQM823L, i. e. no LCD support
- make TQM823L_LCD_defconfig
- - will configure for a TQM823L with U-Boot console on LCD
- etc.
- Finally, type "make all", and you should get some working U-Boot
- images ready for download to / installation on your system:
- - "u-boot.bin" is a raw binary image
- - "u-boot" is an image in ELF binary format
- - "u-boot.srec" is in Motorola S-Record format
- By default the build is performed locally and the objects are saved
- in the source directory. One of the two methods can be used to change
- this behavior and build U-Boot to some external directory:
- 1. Add O= to the make command line invocations:
- make O=/tmp/build distclean
- make O=/tmp/build NAME_defconfig
- make O=/tmp/build all
- 2. Set environment variable KBUILD_OUTPUT to point to the desired location:
- export KBUILD_OUTPUT=/tmp/build
- make distclean
- make NAME_defconfig
- make all
- Note that the command line "O=" setting overrides the KBUILD_OUTPUT environment
- variable.
- User specific CPPFLAGS, AFLAGS and CFLAGS can be passed to the compiler by
- setting the according environment variables KCPPFLAGS, KAFLAGS and KCFLAGS.
- For example to treat all compiler warnings as errors:
- make KCFLAGS=-Werror
- Please be aware that the Makefiles assume you are using GNU make, so
- for instance on NetBSD you might need to use "gmake" instead of
- native "make".
- If the system board that you have is not listed, then you will need
- to port U-Boot to your hardware platform. To do this, follow these
- steps:
- 1. Create a new directory to hold your board specific code. Add any
- files you need. In your board directory, you will need at least
- the "Makefile" and a "<board>.c".
- 2. Create a new configuration file "include/configs/<board>.h" for
- your board.
- 3. If you're porting U-Boot to a new CPU, then also create a new
- directory to hold your CPU specific code. Add any files you need.
- 4. Run "make <board>_defconfig" with your new name.
- 5. Type "make", and you should get a working "u-boot.srec" file
- to be installed on your target system.
- 6. Debug and solve any problems that might arise.
- [Of course, this last step is much harder than it sounds.]
- Testing of U-Boot Modifications, Ports to New Hardware, etc.:
- ==============================================================
- If you have modified U-Boot sources (for instance added a new board
- or support for new devices, a new CPU, etc.) you are expected to
- provide feedback to the other developers. The feedback normally takes
- the form of a "patch", i.e. a context diff against a certain (latest
- official or latest in the git repository) version of U-Boot sources.
- But before you submit such a patch, please verify that your modifi-
- cation did not break existing code. At least make sure that *ALL* of
- the supported boards compile WITHOUT ANY compiler warnings. To do so,
- just run the buildman script (tools/buildman/buildman), which will
- configure and build U-Boot for ALL supported system. Be warned, this
- will take a while. Please see the buildman README, or run 'buildman -H'
- for documentation.
- See also "U-Boot Porting Guide" below.
- Monitor Commands - Overview:
- ============================
- go - start application at address 'addr'
- run - run commands in an environment variable
- bootm - boot application image from memory
- bootp - boot image via network using BootP/TFTP protocol
- bootz - boot zImage from memory
- tftpboot- boot image via network using TFTP protocol
- and env variables "ipaddr" and "serverip"
- (and eventually "gatewayip")
- tftpput - upload a file via network using TFTP protocol
- rarpboot- boot image via network using RARP/TFTP protocol
- diskboot- boot from IDE devicebootd - boot default, i.e., run 'bootcmd'
- loads - load S-Record file over serial line
- loadb - load binary file over serial line (kermit mode)
- loadm - load binary blob from source address to destination address
- md - memory display
- mm - memory modify (auto-incrementing)
- nm - memory modify (constant address)
- mw - memory write (fill)
- ms - memory search
- cp - memory copy
- cmp - memory compare
- crc32 - checksum calculation
- i2c - I2C sub-system
- sspi - SPI utility commands
- base - print or set address offset
- printenv- print environment variables
- pwm - control pwm channels
- seama - load SEAMA NAND image
- setenv - set environment variables
- saveenv - save environment variables to persistent storage
- protect - enable or disable FLASH write protection
- erase - erase FLASH memory
- flinfo - print FLASH memory information
- nand - NAND memory operations (see doc/README.nand)
- bdinfo - print Board Info structure
- iminfo - print header information for application image
- coninfo - print console devices and informations
- ide - IDE sub-system
- loop - infinite loop on address range
- loopw - infinite write loop on address range
- mtest - simple RAM test
- icache - enable or disable instruction cache
- dcache - enable or disable data cache
- reset - Perform RESET of the CPU
- echo - echo args to console
- version - print monitor version
- help - print online help
- ? - alias for 'help'
- Monitor Commands - Detailed Description:
- ========================================
- TODO.
- For now: just type "help <command>".
- Note for Redundant Ethernet Interfaces:
- =======================================
- Some boards come with redundant Ethernet interfaces; U-Boot supports
- such configurations and is capable of automatic selection of a
- "working" interface when needed. MAC assignment works as follows:
- Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
- MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
- "eth1addr" (=>eth1), "eth2addr", ...
- If the network interface stores some valid MAC address (for instance
- in SROM), this is used as default address if there is NO correspon-
- ding setting in the environment; if the corresponding environment
- variable is set, this overrides the settings in the card; that means:
- o If the SROM has a valid MAC address, and there is no address in the
- environment, the SROM's address is used.
- o If there is no valid address in the SROM, and a definition in the
- environment exists, then the value from the environment variable is
- used.
- o If both the SROM and the environment contain a MAC address, and
- both addresses are the same, this MAC address is used.
- o If both the SROM and the environment contain a MAC address, and the
- addresses differ, the value from the environment is used and a
- warning is printed.
- o If neither SROM nor the environment contain a MAC address, an error
- is raised. If CONFIG_NET_RANDOM_ETHADDR is defined, then in this case
- a random, locally-assigned MAC is used.
- If Ethernet drivers implement the 'write_hwaddr' function, valid MAC addresses
- will be programmed into hardware as part of the initialization process. This
- may be skipped by setting the appropriate 'ethmacskip' environment variable.
- The naming convention is as follows:
- "ethmacskip" (=>eth0), "eth1macskip" (=>eth1) etc.
- Image Formats:
- ==============
- U-Boot is capable of booting (and performing other auxiliary operations on)
- images in two formats:
- New uImage format (FIT)
- -----------------------
- Flexible and powerful format based on Flattened Image Tree -- FIT (similar
- to Flattened Device Tree). It allows the use of images with multiple
- components (several kernels, ramdisks, etc.), with contents protected by
- SHA1, MD5 or CRC32. More details are found in the doc/uImage.FIT directory.
- Old uImage format
- -----------------
- Old image format is based on binary files which can be basically anything,
- preceded by a special header; see the definitions in include/image.h for
- details; basically, the header defines the following image properties:
- * Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
- 4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
- LynxOS, pSOS, QNX, RTEMS, INTEGRITY;
- Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, INTEGRITY).
- * Target CPU Architecture (Provisions for Alpha, ARM, Intel x86,
- IA64, MIPS, Nios II, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
- Currently supported: ARM, Intel x86, MIPS, Nios II, PowerPC).
- * Compression Type (uncompressed, gzip, bzip2)
- * Load Address
- * Entry Point
- * Image Name
- * Image Timestamp
- The header is marked by a special Magic Number, and both the header
- and the data portions of the image are secured against corruption by
- CRC32 checksums.
- Linux Support:
- ==============
- Although U-Boot should support any OS or standalone application
- easily, the main focus has always been on Linux during the design of
- U-Boot.
- U-Boot includes many features that so far have been part of some
- special "boot loader" code within the Linux kernel. Also, any
- "initrd" images to be used are no longer part of one big Linux image;
- instead, kernel and "initrd" are separate images. This implementation
- serves several purposes:
- - the same features can be used for other OS or standalone
- applications (for instance: using compressed images to reduce the
- Flash memory footprint)
- - it becomes much easier to port new Linux kernel versions because
- lots of low-level, hardware dependent stuff are done by U-Boot
- - the same Linux kernel image can now be used with different "initrd"
- images; of course this also means that different kernel images can
- be run with the same "initrd". This makes testing easier (you don't
- have to build a new "zImage.initrd" Linux image when you just
- change a file in your "initrd"). Also, a field-upgrade of the
- software is easier now.
- Linux HOWTO:
- ============
- Porting Linux to U-Boot based systems:
- ---------------------------------------
- U-Boot cannot save you from doing all the necessary modifications to
- configure the Linux device drivers for use with your target hardware
- (no, we don't intend to provide a full virtual machine interface to
- Linux :-).
- But now you can ignore ALL boot loader code (in arch/powerpc/mbxboot).
- Just make sure your machine specific header file (for instance
- include/asm-ppc/tqm8xx.h) includes the same definition of the Board
- Information structure as we define in include/asm-<arch>/u-boot.h,
- and make sure that your definition of IMAP_ADDR uses the same value
- as your U-Boot configuration in CONFIG_SYS_IMMR.
- Note that U-Boot now has a driver model, a unified model for drivers.
- If you are adding a new driver, plumb it into driver model. If there
- is no uclass available, you are encouraged to create one. See
- doc/driver-model.
- Configuring the Linux kernel:
- -----------------------------
- No specific requirements for U-Boot. Make sure you have some root
- device (initial ramdisk, NFS) for your target system.
- Building a Linux Image:
- -----------------------
- With U-Boot, "normal" build targets like "zImage" or "bzImage" are
- not used. If you use recent kernel source, a new build target
- "uImage" will exist which automatically builds an image usable by
- U-Boot. Most older kernels also have support for a "pImage" target,
- which was introduced for our predecessor project PPCBoot and uses a
- 100% compatible format.
- Example:
- make TQM850L_defconfig
- make oldconfig
- make dep
- make uImage
- The "uImage" build target uses a special tool (in 'tools/mkimage') to
- encapsulate a compressed Linux kernel image with header information,
- CRC32 checksum etc. for use with U-Boot. This is what we are doing:
- * build a standard "vmlinux" kernel image (in ELF binary format):
- * convert the kernel into a raw binary image:
- ${CROSS_COMPILE}-objcopy -O binary \
- -R .note -R .comment \
- -S vmlinux linux.bin
- * compress the binary image:
- gzip -9 linux.bin
- * package compressed binary image for U-Boot:
- mkimage -A ppc -O linux -T kernel -C gzip \
- -a 0 -e 0 -n "Linux Kernel Image" \
- -d linux.bin.gz uImage
- The "mkimage" tool can also be used to create ramdisk images for use
- with U-Boot, either separated from the Linux kernel image, or
- combined into one file. "mkimage" encapsulates the images with a 64
- byte header containing information about target architecture,
- operating system, image type, compression method, entry points, time
- stamp, CRC32 checksums, etc.
- "mkimage" can be called in two ways: to verify existing images and
- print the header information, or to build new images.
- In the first form (with "-l" option) mkimage lists the information
- contained in the header of an existing U-Boot image; this includes
- checksum verification:
- tools/mkimage -l image
- -l ==> list image header information
- The second form (with "-d" option) is used to build a U-Boot image
- from a "data file" which is used as image payload:
- tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
- -n name -d data_file image
- -A ==> set architecture to 'arch'
- -O ==> set operating system to 'os'
- -T ==> set image type to 'type'
- -C ==> set compression type 'comp'
- -a ==> set load address to 'addr' (hex)
- -e ==> set entry point to 'ep' (hex)
- -n ==> set image name to 'name'
- -d ==> use image data from 'datafile'
- Right now, all Linux kernels for PowerPC systems use the same load
- address (0x00000000), but the entry point address depends on the
- kernel version:
- - 2.2.x kernels have the entry point at 0x0000000C,
- - 2.3.x and later kernels have the entry point at 0x00000000.
- So a typical call to build a U-Boot image would read:
- -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
- > -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
- > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz \
- > examples/uImage.TQM850L
- Image Name: 2.4.4 kernel for TQM850L
- Created: Wed Jul 19 02:34:59 2000
- Image Type: PowerPC Linux Kernel Image (gzip compressed)
- Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
- Load Address: 0x00000000
- Entry Point: 0x00000000
- To verify the contents of the image (or check for corruption):
- -> tools/mkimage -l examples/uImage.TQM850L
- Image Name: 2.4.4 kernel for TQM850L
- Created: Wed Jul 19 02:34:59 2000
- Image Type: PowerPC Linux Kernel Image (gzip compressed)
- Data Size: 335725 Bytes = 327.86 kB = 0.32 MB
- Load Address: 0x00000000
- Entry Point: 0x00000000
- NOTE: for embedded systems where boot time is critical you can trade
- speed for memory and install an UNCOMPRESSED image instead: this
- needs more space in Flash, but boots much faster since it does not
- need to be uncompressed:
- -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux.gz
- -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
- > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
- > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/powerpc/coffboot/vmlinux \
- > examples/uImage.TQM850L-uncompressed
- Image Name: 2.4.4 kernel for TQM850L
- Created: Wed Jul 19 02:34:59 2000
- Image Type: PowerPC Linux Kernel Image (uncompressed)
- Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
- Load Address: 0x00000000
- Entry Point: 0x00000000
- Similar you can build U-Boot images from a 'ramdisk.image.gz' file
- when your kernel is intended to use an initial ramdisk:
- -> tools/mkimage -n 'Simple Ramdisk Image' \
- > -A ppc -O linux -T ramdisk -C gzip \
- > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
- Image Name: Simple Ramdisk Image
- Created: Wed Jan 12 14:01:50 2000
- Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
- Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
- Load Address: 0x00000000
- Entry Point: 0x00000000
- The "dumpimage" tool can be used to disassemble or list the contents of images
- built by mkimage. See dumpimage's help output (-h) for details.
- Installing a Linux Image:
- -------------------------
- To downloading a U-Boot image over the serial (console) interface,
- you must convert the image to S-Record format:
- objcopy -I binary -O srec examples/image examples/image.srec
- The 'objcopy' does not understand the information in the U-Boot
- image header, so the resulting S-Record file will be relative to
- address 0x00000000. To load it to a given address, you need to
- specify the target address as 'offset' parameter with the 'loads'
- command.
- Example: install the image to address 0x40100000 (which on the
- TQM8xxL is in the first Flash bank):
- => erase 40100000 401FFFFF
- .......... done
- Erased 8 sectors
- => loads 40100000
- ## Ready for S-Record download ...
- ~>examples/image.srec
- 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
- ...
- 15989 15990 15991 15992
- [file transfer complete]
- [connected]
- ## Start Addr = 0x00000000
- You can check the success of the download using the 'iminfo' command;
- this includes a checksum verification so you can be sure no data
- corruption happened:
- => imi 40100000
- ## Checking Image at 40100000 ...
- Image Name: 2.2.13 for initrd on TQM850L
- Image Type: PowerPC Linux Kernel Image (gzip compressed)
- Data Size: 335725 Bytes = 327 kB = 0 MB
- Load Address: 00000000
- Entry Point: 0000000c
- Verifying Checksum ... OK
- Boot Linux:
- -----------
- The "bootm" command is used to boot an application that is stored in
- memory (RAM or Flash). In case of a Linux kernel image, the contents
- of the "bootargs" environment variable is passed to the kernel as
- parameters. You can check and modify this variable using the
- "printenv" and "setenv" commands:
- => printenv bootargs
- bootargs=root=/dev/ram
- => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
- => printenv bootargs
- bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
- => bootm 40020000
- ## Booting Linux kernel at 40020000 ...
- Image Name: 2.2.13 for NFS on TQM850L
- Image Type: PowerPC Linux Kernel Image (gzip compressed)
- Data Size: 381681 Bytes = 372 kB = 0 MB
- Load Address: 00000000
- Entry Point: 0000000c
- Verifying Checksum ... OK
- Uncompressing Kernel Image ... OK
- 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
- Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
- time_init: decrementer frequency = 187500000/60
- Calibrating delay loop... 49.77 BogoMIPS
- Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
- ...
- If you want to boot a Linux kernel with initial RAM disk, you pass
- the memory addresses of both the kernel and the initrd image (PPBCOOT
- format!) to the "bootm" command:
- => imi 40100000 40200000
- ## Checking Image at 40100000 ...
- Image Name: 2.2.13 for initrd on TQM850L
- Image Type: PowerPC Linux Kernel Image (gzip compressed)
- Data Size: 335725 Bytes = 327 kB = 0 MB
- Load Address: 00000000
- Entry Point: 0000000c
- Verifying Checksum ... OK
- ## Checking Image at 40200000 ...
- Image Name: Simple Ramdisk Image
- Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
- Data Size: 566530 Bytes = 553 kB = 0 MB
- Load Address: 00000000
- Entry Point: 00000000
- Verifying Checksum ... OK
- => bootm 40100000 40200000
- ## Booting Linux kernel at 40100000 ...
- Image Name: 2.2.13 for initrd on TQM850L
- Image Type: PowerPC Linux Kernel Image (gzip compressed)
- Data Size: 335725 Bytes = 327 kB = 0 MB
- Load Address: 00000000
- Entry Point: 0000000c
- Verifying Checksum ... OK
- Uncompressing Kernel Image ... OK
- ## Loading RAMDisk Image at 40200000 ...
- Image Name: Simple Ramdisk Image
- Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
- Data Size: 566530 Bytes = 553 kB = 0 MB
- Load Address: 00000000
- Entry Point: 00000000
- Verifying Checksum ... OK
- Loading Ramdisk ... OK
- 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
- Boot arguments: root=/dev/ram
- time_init: decrementer frequency = 187500000/60
- Calibrating delay loop... 49.77 BogoMIPS
- ...
- RAMDISK: Compressed image found at block 0
- VFS: Mounted root (ext2 filesystem).
- bash#
- Boot Linux and pass a flat device tree:
- -----------
- First, U-Boot must be compiled with the appropriate defines. See the section
- titled "Linux Kernel Interface" above for a more in depth explanation. The
- following is an example of how to start a kernel and pass an updated
- flat device tree:
- => print oftaddr
- oftaddr=0x300000
- => print oft
- oft=oftrees/mpc8540ads.dtb
- => tftp $oftaddr $oft
- Speed: 1000, full duplex
- Using TSEC0 device
- TFTP from server 192.168.1.1; our IP address is 192.168.1.101
- Filename 'oftrees/mpc8540ads.dtb'.
- Load address: 0x300000
- Loading: #
- done
- Bytes transferred = 4106 (100a hex)
- => tftp $loadaddr $bootfile
- Speed: 1000, full duplex
- Using TSEC0 device
- TFTP from server 192.168.1.1; our IP address is 192.168.1.2
- Filename 'uImage'.
- Load address: 0x200000
- Loading:############
- done
- Bytes transferred = 1029407 (fb51f hex)
- => print loadaddr
- loadaddr=200000
- => print oftaddr
- oftaddr=0x300000
- => bootm $loadaddr - $oftaddr
- ## Booting image at 00200000 ...
- Image Name: Linux-2.6.17-dirty
- Image Type: PowerPC Linux Kernel Image (gzip compressed)
- Data Size: 1029343 Bytes = 1005.2 kB
- Load Address: 00000000
- Entry Point: 00000000
- Verifying Checksum ... OK
- Uncompressing Kernel Image ... OK
- Booting using flat device tree at 0x300000
- Using MPC85xx ADS machine description
- Memory CAM mapping: CAM0=256Mb, CAM1=256Mb, CAM2=0Mb residual: 0Mb
- [snip]
- More About U-Boot Image Types:
- ------------------------------
- U-Boot supports the following image types:
- "Standalone Programs" are directly runnable in the environment
- provided by U-Boot; it is expected that (if they behave
- well) you can continue to work in U-Boot after return from
- the Standalone Program.
- "OS Kernel Images" are usually images of some Embedded OS which
- will take over control completely. Usually these programs
- will install their own set of exception handlers, device
- drivers, set up the MMU, etc. - this means, that you cannot
- expect to re-enter U-Boot except by resetting the CPU.
- "RAMDisk Images" are more or less just data blocks, and their
- parameters (address, size) are passed to an OS kernel that is
- being started.
- "Multi-File Images" contain several images, typically an OS
- (Linux) kernel image and one or more data images like
- RAMDisks. This construct is useful for instance when you want
- to boot over the network using BOOTP etc., where the boot
- server provides just a single image file, but you want to get
- for instance an OS kernel and a RAMDisk image.
- "Multi-File Images" start with a list of image sizes, each
- image size (in bytes) specified by an "uint32_t" in network
- byte order. This list is terminated by an "(uint32_t)0".
- Immediately after the terminating 0 follow the images, one by
- one, all aligned on "uint32_t" boundaries (size rounded up to
- a multiple of 4 bytes).
- "Firmware Images" are binary images containing firmware (like
- U-Boot or FPGA images) which usually will be programmed to
- flash memory.
- "Script files" are command sequences that will be executed by
- U-Boot's command interpreter; this feature is especially
- useful when you configure U-Boot to use a real shell (hush)
- as command interpreter.
- Booting the Linux zImage:
- -------------------------
- On some platforms, it's possible to boot Linux zImage. This is done
- using the "bootz" command. The syntax of "bootz" command is the same
- as the syntax of "bootm" command.
- Note, defining the CONFIG_SUPPORT_RAW_INITRD allows user to supply
- kernel with raw initrd images. The syntax is slightly different, the
- address of the initrd must be augmented by it's size, in the following
- format: "<initrd addres>:<initrd size>".
- Standalone HOWTO:
- =================
- One of the features of U-Boot is that you can dynamically load and
- run "standalone" applications, which can use some resources of
- U-Boot like console I/O functions or interrupt services.
- Two simple examples are included with the sources:
- "Hello World" Demo:
- -------------------
- 'examples/hello_world.c' contains a small "Hello World" Demo
- application; it is automatically compiled when you build U-Boot.
- It's configured to run at address 0x00040004, so you can play with it
- like that:
- => loads
- ## Ready for S-Record download ...
- ~>examples/hello_world.srec
- 1 2 3 4 5 6 7 8 9 10 11 ...
- [file transfer complete]
- [connected]
- ## Start Addr = 0x00040004
- => go 40004 Hello World! This is a test.
- ## Starting application at 0x00040004 ...
- Hello World
- argc = 7
- argv[0] = "40004"
- argv[1] = "Hello"
- argv[2] = "World!"
- argv[3] = "This"
- argv[4] = "is"
- argv[5] = "a"
- argv[6] = "test."
- argv[7] = "<NULL>"
- Hit any key to exit ...
- ## Application terminated, rc = 0x0
- Another example, which demonstrates how to register a CPM interrupt
- handler with the U-Boot code, can be found in 'examples/timer.c'.
- Here, a CPM timer is set up to generate an interrupt every second.
- The interrupt service routine is trivial, just printing a '.'
- character, but this is just a demo program. The application can be
- controlled by the following keys:
- ? - print current values og the CPM Timer registers
- b - enable interrupts and start timer
- e - stop timer and disable interrupts
- q - quit application
- => loads
- ## Ready for S-Record download ...
- ~>examples/timer.srec
- 1 2 3 4 5 6 7 8 9 10 11 ...
- [file transfer complete]
- [connected]
- ## Start Addr = 0x00040004
- => go 40004
- ## Starting application at 0x00040004 ...
- TIMERS=0xfff00980
- Using timer 1
- tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
- Hit 'b':
- [q, b, e, ?] Set interval 1000000 us
- Enabling timer
- Hit '?':
- [q, b, e, ?] ........
- tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
- Hit '?':
- [q, b, e, ?] .
- tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
- Hit '?':
- [q, b, e, ?] .
- tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
- Hit '?':
- [q, b, e, ?] .
- tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
- Hit 'e':
- [q, b, e, ?] ...Stopping timer
- Hit 'q':
- [q, b, e, ?] ## Application terminated, rc = 0x0
- Implementation Internals:
- =========================
- The following is not intended to be a complete description of every
- implementation detail. However, it should help to understand the
- inner workings of U-Boot and make it easier to port it to custom
- hardware.
- Initial Stack, Global Data:
- ---------------------------
- The implementation of U-Boot is complicated by the fact that U-Boot
- starts running out of ROM (flash memory), usually without access to
- system RAM (because the memory controller is not initialized yet).
- This means that we don't have writable Data or BSS segments, and BSS
- is not initialized as zero. To be able to get a C environment working
- at all, we have to allocate at least a minimal stack. Implementation
- options for this are defined and restricted by the CPU used: Some CPU
- models provide on-chip memory (like the IMMR area on MPC8xx and
- MPC826x processors), on others (parts of) the data cache can be
- locked as (mis-) used as memory, etc.
- Chris Hallinan posted a good summary of these issues to the
- U-Boot mailing list:
- Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
- From: "Chris Hallinan" <clh@net1plus.com>
- Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
- ...
- Correct me if I'm wrong, folks, but the way I understand it
- is this: Using DCACHE as initial RAM for Stack, etc, does not
- require any physical RAM backing up the cache. The cleverness
- is that the cache is being used as a temporary supply of
- necessary storage before the SDRAM controller is setup. It's
- beyond the scope of this list to explain the details, but you
- can see how this works by studying the cache architecture and
- operation in the architecture and processor-specific manuals.
- OCM is On Chip Memory, which I believe the 405GP has 4K. It
- is another option for the system designer to use as an
- initial stack/RAM area prior to SDRAM being available. Either
- option should work for you. Using CS 4 should be fine if your
- board designers haven't used it for something that would
- cause you grief during the initial boot! It is frequently not
- used.
- CFG_SYS_INIT_RAM_ADDR should be somewhere that won't interfere
- with your processor/board/system design. The default value
- you will find in any recent u-boot distribution in
- walnut.h should work for you. I'd set it to a value larger
- than your SDRAM module. If you have a 64MB SDRAM module, set
- it above 400_0000. Just make sure your board has no resources
- that are supposed to respond to that address! That code in
- start.S has been around a while and should work as is when
- you get the config right.
- -Chris Hallinan
- DS4.COM, Inc.
- It is essential to remember this, since it has some impact on the C
- code for the initialization procedures:
- * Initialized global data (data segment) is read-only. Do not attempt
- to write it.
- * Do not use any uninitialized global data (or implicitly initialized
- as zero data - BSS segment) at all - this is undefined, initiali-
- zation is performed later (when relocating to RAM).
- * Stack space is very limited. Avoid big data buffers or things like
- that.
- Having only the stack as writable memory limits means we cannot use
- normal global data to share information between the code. But it
- turned out that the implementation of U-Boot can be greatly
- simplified by making a global data structure (gd_t) available to all
- functions. We could pass a pointer to this data as argument to _all_
- functions, but this would bloat the code. Instead we use a feature of
- the GCC compiler (Global Register Variables) to share the data: we
- place a pointer (gd) to the global data into a register which we
- reserve for this purpose.
- When choosing a register for such a purpose we are restricted by the
- relevant (E)ABI specifications for the current architecture, and by
- GCC's implementation.
- For PowerPC, the following registers have specific use:
- R1: stack pointer
- R2: reserved for system use
- R3-R4: parameter passing and return values
- R5-R10: parameter passing
- R13: small data area pointer
- R30: GOT pointer
- R31: frame pointer
- (U-Boot also uses R12 as internal GOT pointer. r12
- is a volatile register so r12 needs to be reset when
- going back and forth between asm and C)
- ==> U-Boot will use R2 to hold a pointer to the global data
- Note: on PPC, we could use a static initializer (since the
- address of the global data structure is known at compile time),
- but it turned out that reserving a register results in somewhat
- smaller code - although the code savings are not that big (on
- average for all boards 752 bytes for the whole U-Boot image,
- 624 text + 127 data).
- On ARM, the following registers are used:
- R0: function argument word/integer result
- R1-R3: function argument word
- R9: platform specific
- R10: stack limit (used only if stack checking is enabled)
- R11: argument (frame) pointer
- R12: temporary workspace
- R13: stack pointer
- R14: link register
- R15: program counter
- ==> U-Boot will use R9 to hold a pointer to the global data
- Note: on ARM, only R_ARM_RELATIVE relocations are supported.
- On Nios II, the ABI is documented here:
- https://www.altera.com/literature/hb/nios2/n2cpu_nii51016.pdf
- ==> U-Boot will use gp to hold a pointer to the global data
- Note: on Nios II, we give "-G0" option to gcc and don't use gp
- to access small data sections, so gp is free.
- On RISC-V, the following registers are used:
- x0: hard-wired zero (zero)
- x1: return address (ra)
- x2: stack pointer (sp)
- x3: global pointer (gp)
- x4: thread pointer (tp)
- x5: link register (t0)
- x8: frame pointer (fp)
- x10-x11: arguments/return values (a0-1)
- x12-x17: arguments (a2-7)
- x28-31: temporaries (t3-6)
- pc: program counter (pc)
- ==> U-Boot will use gp to hold a pointer to the global data
- Memory Management:
- ------------------
- U-Boot runs in system state and uses physical addresses, i.e. the
- MMU is not used either for address mapping nor for memory protection.
- The available memory is mapped to fixed addresses using the memory
- controller. In this process, a contiguous block is formed for each
- memory type (Flash, SDRAM, SRAM), even when it consists of several
- physical memory banks.
- U-Boot is installed in the first 128 kB of the first Flash bank (on
- TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
- booting and sizing and initializing DRAM, the code relocates itself
- to the upper end of DRAM. Immediately below the U-Boot code some
- memory is reserved for use by malloc() [see CONFIG_SYS_MALLOC_LEN
- configuration setting]. Below that, a structure with global Board
- Info data is placed, followed by the stack (growing downward).
- Additionally, some exception handler code is copied to the low 8 kB
- of DRAM (0x00000000 ... 0x00001FFF).
- So a typical memory configuration with 16 MB of DRAM could look like
- this:
- 0x0000 0000 Exception Vector code
- :
- 0x0000 1FFF
- 0x0000 2000 Free for Application Use
- :
- :
- :
- :
- 0x00FB FF20 Monitor Stack (Growing downward)
- 0x00FB FFAC Board Info Data and permanent copy of global data
- 0x00FC 0000 Malloc Arena
- :
- 0x00FD FFFF
- 0x00FE 0000 RAM Copy of Monitor Code
- ... eventually: LCD or video framebuffer
- ... eventually: pRAM (Protected RAM - unchanged by reset)
- 0x00FF FFFF [End of RAM]
- System Initialization:
- ----------------------
- In the reset configuration, U-Boot starts at the reset entry point
- (on most PowerPC systems at address 0x00000100). Because of the reset
- configuration for CS0# this is a mirror of the on board Flash memory.
- To be able to re-map memory U-Boot then jumps to its link address.
- To be able to implement the initialization code in C, a (small!)
- initial stack is set up in the internal Dual Ported RAM (in case CPUs
- which provide such a feature like), or in a locked part of the data
- cache. After that, U-Boot initializes the CPU core, the caches and
- the SIU.
- Next, all (potentially) available memory banks are mapped using a
- preliminary mapping. For example, we put them on 512 MB boundaries
- (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
- on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
- programmed for SDRAM access. Using the temporary configuration, a
- simple memory test is run that determines the size of the SDRAM
- banks.
- When there is more than one SDRAM bank, and the banks are of
- different size, the largest is mapped first. For equal size, the first
- bank (CS2#) is mapped first. The first mapping is always for address
- 0x00000000, with any additional banks following immediately to create
- contiguous memory starting from 0.
- Then, the monitor installs itself at the upper end of the SDRAM area
- and allocates memory for use by malloc() and for the global Board
- Info data; also, the exception vector code is copied to the low RAM
- pages, and the final stack is set up.
- Only after this relocation will you have a "normal" C environment;
- until that you are restricted in several ways, mostly because you are
- running from ROM, and because the code will have to be relocated to a
- new address in RAM.
- Contributing
- ============
- The U-Boot projects depends on contributions from the user community.
- If you want to participate, please, have a look at the 'General'
- section of https://u-boot.readthedocs.io/en/latest/develop/index.html
- where we describe coding standards and the patch submission process.
|