x86.rst 31 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529530531532533534535536537538539540541542543544545546547548549550551552553554555556557558559560561562563564565566567568569570571572573574575576577578579580581582583584585586587588589590591592593594595596597598599600601602603604605606607608609610611612613614615616617618619620621622623624625626627628629630631632633634635636637638639640641642643644645646647648649650651652653654655656657658659660661662663664665666667668669670671672673674675676677678679680681682683684685686687688689690691692693694695696697698699700701702703704705706707708709710711712713714715716717718719720721722723724725726727728729730731732733734735736737738739740741742743744745746747748749750751752753754755756757758759760761762763764765
  1. .. SPDX-License-Identifier: GPL-2.0+
  2. .. Copyright (C) 2014, Simon Glass <sjg@chromium.org>
  3. .. Copyright (C) 2014, Bin Meng <bmeng.cn@gmail.com>
  4. x86
  5. ===
  6. This document describes the information about U-Boot running on x86 targets,
  7. including supported boards, build instructions, todo list, etc.
  8. Status
  9. ------
  10. U-Boot supports running as a `coreboot`_ payload on x86. So far only Link
  11. (Chromebook Pixel) and `QEMU`_ x86 targets have been tested, but it should
  12. work with minimal adjustments on other x86 boards since coreboot deals with
  13. most of the low-level details.
  14. U-Boot is a main bootloader on Intel Edison board.
  15. U-Boot also supports booting directly from x86 reset vector, without coreboot.
  16. In this case, known as bare mode, from the fact that it runs on the
  17. 'bare metal', U-Boot acts like a BIOS replacement. The following platforms
  18. are supported:
  19. - Bayley Bay CRB
  20. - Cherry Hill CRB
  21. - Congatec QEVAL 2.0 & conga-QA3/E3845
  22. - Cougar Canyon 2 CRB
  23. - Crown Bay CRB
  24. - Galileo
  25. - Link (Chromebook Pixel)
  26. - Minnowboard MAX
  27. - Samus (Chromebook Pixel 2015)
  28. - QEMU x86 (32-bit & 64-bit)
  29. As for loading an OS, U-Boot supports directly booting a 32-bit or 64-bit
  30. Linux kernel as part of a FIT image. It also supports a compressed zImage.
  31. U-Boot supports loading an x86 VxWorks kernel. Please check README.vxworks
  32. for more details.
  33. Build Instructions for U-Boot as BIOS replacement (bare mode)
  34. -------------------------------------------------------------
  35. Building a ROM version of U-Boot (hereafter referred to as u-boot.rom) is a
  36. little bit tricky, as generally it requires several binary blobs which are not
  37. shipped in the U-Boot source tree. Due to this reason, the u-boot.rom build is
  38. not turned on by default in the U-Boot source tree. Firstly, you need turn it
  39. on by enabling the ROM build either via an environment variable::
  40. $ export BUILD_ROM=y
  41. or via configuration::
  42. CONFIG_BUILD_ROM=y
  43. Both tell the Makefile to build u-boot.rom as a target.
  44. CPU Microcode
  45. -------------
  46. Modern CPUs usually require a special bit stream called `microcode`_ to be
  47. loaded on the processor after power up in order to function properly. U-Boot
  48. has already integrated these as hex dumps in the source tree.
  49. SMP Support
  50. -----------
  51. On a multicore system, U-Boot is executed on the bootstrap processor (BSP).
  52. Additional application processors (AP) can be brought up by U-Boot. In order to
  53. have an SMP kernel to discover all of the available processors, U-Boot needs to
  54. prepare configuration tables which contain the multi-CPUs information before
  55. loading the OS kernel. Currently U-Boot supports generating two types of tables
  56. for SMP, called Simple Firmware Interface (`SFI`_) and Multi-Processor (`MP`_)
  57. tables. The writing of these two tables are controlled by two Kconfig
  58. options GENERATE_SFI_TABLE and GENERATE_MP_TABLE.
  59. Driver Model
  60. ------------
  61. x86 has been converted to use driver model for serial, GPIO, SPI, SPI flash,
  62. keyboard, real-time clock, USB. Video is in progress.
  63. Device Tree
  64. -----------
  65. x86 uses device tree to configure the board thus requires CONFIG_OF_CONTROL to
  66. be turned on. Not every device on the board is configured via device tree, but
  67. more and more devices will be added as time goes by. Check out the directory
  68. arch/x86/dts/ for these device tree source files.
  69. Useful Commands
  70. ---------------
  71. In keeping with the U-Boot philosophy of providing functions to check and
  72. adjust internal settings, there are several x86-specific commands that may be
  73. useful:
  74. fsp
  75. Display information about Intel Firmware Support Package (FSP).
  76. This is only available on platforms which use FSP, mostly Atom.
  77. iod
  78. Display I/O memory
  79. iow
  80. Write I/O memory
  81. mtrr
  82. List and set the Memory Type Range Registers (MTRR). These are used to
  83. tell the CPU whether memory is cacheable and if so the cache write
  84. mode to use. U-Boot sets up some reasonable values but you can
  85. adjust then with this command.
  86. Booting Ubuntu
  87. --------------
  88. As an example of how to set up your boot flow with U-Boot, here are
  89. instructions for starting Ubuntu from U-Boot. These instructions have been
  90. tested on Minnowboard MAX with a SATA drive but are equally applicable on
  91. other platforms and other media. There are really only four steps and it's a
  92. very simple script, but a more detailed explanation is provided here for
  93. completeness.
  94. Note: It is possible to set up U-Boot to boot automatically using syslinux.
  95. It could also use the grub.cfg file (/efi/ubuntu/grub.cfg) to obtain the
  96. GUID. If you figure these out, please post patches to this README.
  97. Firstly, you will need Ubuntu installed on an available disk. It should be
  98. possible to make U-Boot start a USB start-up disk but for now let's assume
  99. that you used another boot loader to install Ubuntu.
  100. Use the U-Boot command line to find the UUID of the partition you want to
  101. boot. For example our disk is SCSI device 0::
  102. => part list scsi 0
  103. Partition Map for SCSI device 0 -- Partition Type: EFI
  104. Part Start LBA End LBA Name
  105. Attributes
  106. Type GUID
  107. Partition GUID
  108. 1 0x00000800 0x001007ff ""
  109. attrs: 0x0000000000000000
  110. type: c12a7328-f81f-11d2-ba4b-00a0c93ec93b
  111. guid: 9d02e8e4-4d59-408f-a9b0-fd497bc9291c
  112. 2 0x00100800 0x037d8fff ""
  113. attrs: 0x0000000000000000
  114. type: 0fc63daf-8483-4772-8e79-3d69d8477de4
  115. guid: 965c59ee-1822-4326-90d2-b02446050059
  116. 3 0x037d9000 0x03ba27ff ""
  117. attrs: 0x0000000000000000
  118. type: 0657fd6d-a4ab-43c4-84e5-0933c84b4f4f
  119. guid: 2c4282bd-1e82-4bcf-a5ff-51dedbf39f17
  120. =>
  121. This shows that your SCSI disk has three partitions. The really long hex
  122. strings are called Globally Unique Identifiers (GUIDs). You can look up the
  123. 'type' ones `here`_. On this disk the first partition is for EFI and is in
  124. VFAT format (DOS/Windows)::
  125. => fatls scsi 0:1
  126. efi/
  127. 0 file(s), 1 dir(s)
  128. Partition 2 is 'Linux filesystem data' so that will be our root disk. It is
  129. in ext2 format::
  130. => ext2ls scsi 0:2
  131. <DIR> 4096 .
  132. <DIR> 4096 ..
  133. <DIR> 16384 lost+found
  134. <DIR> 4096 boot
  135. <DIR> 12288 etc
  136. <DIR> 4096 media
  137. <DIR> 4096 bin
  138. <DIR> 4096 dev
  139. <DIR> 4096 home
  140. <DIR> 4096 lib
  141. <DIR> 4096 lib64
  142. <DIR> 4096 mnt
  143. <DIR> 4096 opt
  144. <DIR> 4096 proc
  145. <DIR> 4096 root
  146. <DIR> 4096 run
  147. <DIR> 12288 sbin
  148. <DIR> 4096 srv
  149. <DIR> 4096 sys
  150. <DIR> 4096 tmp
  151. <DIR> 4096 usr
  152. <DIR> 4096 var
  153. <SYM> 33 initrd.img
  154. <SYM> 30 vmlinuz
  155. <DIR> 4096 cdrom
  156. <SYM> 33 initrd.img.old
  157. =>
  158. and if you look in the /boot directory you will see the kernel::
  159. => ext2ls scsi 0:2 /boot
  160. <DIR> 4096 .
  161. <DIR> 4096 ..
  162. <DIR> 4096 efi
  163. <DIR> 4096 grub
  164. 3381262 System.map-3.13.0-32-generic
  165. 1162712 abi-3.13.0-32-generic
  166. 165611 config-3.13.0-32-generic
  167. 176500 memtest86+.bin
  168. 178176 memtest86+.elf
  169. 178680 memtest86+_multiboot.bin
  170. 5798112 vmlinuz-3.13.0-32-generic
  171. 165762 config-3.13.0-58-generic
  172. 1165129 abi-3.13.0-58-generic
  173. 5823136 vmlinuz-3.13.0-58-generic
  174. 19215259 initrd.img-3.13.0-58-generic
  175. 3391763 System.map-3.13.0-58-generic
  176. 5825048 vmlinuz-3.13.0-58-generic.efi.signed
  177. 28304443 initrd.img-3.13.0-32-generic
  178. =>
  179. The 'vmlinuz' files contain a packaged Linux kernel. The format is a kind of
  180. self-extracting compressed file mixed with some 'setup' configuration data.
  181. Despite its size (uncompressed it is >10MB) this only includes a basic set of
  182. device drivers, enough to boot on most hardware types.
  183. The 'initrd' files contain a RAM disk. This is something that can be loaded
  184. into RAM and will appear to Linux like a disk. Ubuntu uses this to hold lots
  185. of drivers for whatever hardware you might have. It is loaded before the
  186. real root disk is accessed.
  187. The numbers after the end of each file are the version. Here it is Linux
  188. version 3.13. You can find the source code for this in the Linux tree with
  189. the tag v3.13. The '.0' allows for additional Linux releases to fix problems,
  190. but normally this is not needed. The '-58' is used by Ubuntu. Each time they
  191. release a new kernel they increment this number. New Ubuntu versions might
  192. include kernel patches to fix reported bugs. Stable kernels can exist for
  193. some years so this number can get quite high.
  194. The '.efi.signed' kernel is signed for EFI's secure boot. U-Boot has its own
  195. secure boot mechanism - see `this`_ & `that`_. It cannot read .efi files
  196. at present.
  197. To boot Ubuntu from U-Boot the steps are as follows:
  198. 1. Set up the boot arguments. Use the GUID for the partition you want to boot::
  199. => setenv bootargs root=/dev/disk/by-partuuid/965c59ee-1822-4326-90d2-b02446050059 ro
  200. Here root= tells Linux the location of its root disk. The disk is specified
  201. by its GUID, using '/dev/disk/by-partuuid/', a Linux path to a 'directory'
  202. containing all the GUIDs Linux has found. When it starts up, there will be a
  203. file in that directory with this name in it. It is also possible to use a
  204. device name here, see later.
  205. 2. Load the kernel. Since it is an ext2/4 filesystem we can do::
  206. => ext2load scsi 0:2 03000000 /boot/vmlinuz-3.13.0-58-generic
  207. The address 30000000 is arbitrary, but there seem to be problems with using
  208. small addresses (sometimes Linux cannot find the ramdisk). This is 48MB into
  209. the start of RAM (which is at 0 on x86).
  210. 3. Load the ramdisk (to 64MB)::
  211. => ext2load scsi 0:2 04000000 /boot/initrd.img-3.13.0-58-generic
  212. 4. Start up the kernel. We need to know the size of the ramdisk, but can use
  213. a variable for that. U-Boot sets 'filesize' to the size of the last file it
  214. loaded::
  215. => zboot 03000000 0 04000000 ${filesize}
  216. Type 'help zboot' if you want to see what the arguments are. U-Boot on x86 is
  217. quite verbose when it boots a kernel. You should see these messages from
  218. U-Boot::
  219. Valid Boot Flag
  220. Setup Size = 0x00004400
  221. Magic signature found
  222. Using boot protocol version 2.0c
  223. Linux kernel version 3.13.0-58-generic (buildd@allspice) #97-Ubuntu SMP Wed Jul 8 02:56:15 UTC 2015
  224. Building boot_params at 0x00090000
  225. Loading bzImage at address 100000 (5805728 bytes)
  226. Magic signature found
  227. Initial RAM disk at linear address 0x04000000, size 19215259 bytes
  228. Kernel command line: "root=/dev/disk/by-partuuid/965c59ee-1822-4326-90d2-b02446050059 ro"
  229. Starting kernel ...
  230. U-Boot prints out some bootstage timing. This is more useful if you put the
  231. above commands into a script since then it will be faster::
  232. Timer summary in microseconds:
  233. Mark Elapsed Stage
  234. 0 0 reset
  235. 241,535 241,535 board_init_r
  236. 2,421,611 2,180,076 id=64
  237. 2,421,790 179 id=65
  238. 2,428,215 6,425 main_loop
  239. 48,860,584 46,432,369 start_kernel
  240. Accumulated time:
  241. 240,329 ahci
  242. 1,422,704 vesa display
  243. Now the kernel actually starts (if you want to examine kernel boot up message on
  244. the serial console, append "console=ttyS0,115200" to the kernel command line)::
  245. [ 0.000000] Initializing cgroup subsys cpuset
  246. [ 0.000000] Initializing cgroup subsys cpu
  247. [ 0.000000] Initializing cgroup subsys cpuacct
  248. [ 0.000000] Linux version 3.13.0-58-generic (buildd@allspice) (gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1) ) #97-Ubuntu SMP Wed Jul 8 02:56:15 UTC 2015 (Ubuntu 3.13.0-58.97-generic 3.13.11-ckt22)
  249. [ 0.000000] Command line: root=/dev/disk/by-partuuid/965c59ee-1822-4326-90d2-b02446050059 ro console=ttyS0,115200
  250. It continues for a long time. Along the way you will see it pick up your
  251. ramdisk::
  252. [ 0.000000] RAMDISK: [mem 0x04000000-0x05253fff]
  253. ...
  254. [ 0.788540] Trying to unpack rootfs image as initramfs...
  255. [ 1.540111] Freeing initrd memory: 18768K (ffff880004000000 - ffff880005254000)
  256. ...
  257. Later it actually starts using it::
  258. Begin: Running /scripts/local-premount ... done.
  259. You should also see your boot disk turn up::
  260. [ 4.357243] scsi 1:0:0:0: Direct-Access ATA ADATA SP310 5.2 PQ: 0 ANSI: 5
  261. [ 4.366860] sd 1:0:0:0: [sda] 62533296 512-byte logical blocks: (32.0 GB/29.8 GiB)
  262. [ 4.375677] sd 1:0:0:0: Attached scsi generic sg0 type 0
  263. [ 4.381859] sd 1:0:0:0: [sda] Write Protect is off
  264. [ 4.387452] sd 1:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
  265. [ 4.399535] sda: sda1 sda2 sda3
  266. Linux has found the three partitions (sda1-3). Mercifully it doesn't print out
  267. the GUIDs. In step 1 above we could have used::
  268. setenv bootargs root=/dev/sda2 ro
  269. instead of the GUID. However if you add another drive to your board the
  270. numbering may change whereas the GUIDs will not. So if your boot partition
  271. becomes sdb2, it will still boot. For embedded systems where you just want to
  272. boot the first disk, you have that option.
  273. The last thing you will see on the console is mention of plymouth (which
  274. displays the Ubuntu start-up screen) and a lot of 'Starting' messages::
  275. * Starting Mount filesystems on boot [ OK ]
  276. After a pause you should see a login screen on your display and you are done.
  277. If you want to put this in a script you can use something like this::
  278. setenv bootargs root=UUID=b2aaf743-0418-4d90-94cc-3e6108d7d968 ro
  279. setenv boot zboot 03000000 0 04000000 \${filesize}
  280. setenv bootcmd "ext2load scsi 0:2 03000000 /boot/vmlinuz-3.13.0-58-generic; ext2load scsi 0:2 04000000 /boot/initrd.img-3.13.0-58-generic; run boot"
  281. saveenv
  282. The \ is to tell the shell not to evaluate ${filesize} as part of the setenv
  283. command.
  284. You can also bake this behaviour into your build by hard-coding the
  285. environment variables if you add this to minnowmax.h:
  286. .. code-block:: c
  287. #undef CONFIG_BOOTCOMMAND
  288. #define CONFIG_BOOTCOMMAND \
  289. "ext2load scsi 0:2 03000000 /boot/vmlinuz-3.13.0-58-generic; " \
  290. "ext2load scsi 0:2 04000000 /boot/initrd.img-3.13.0-58-generic; " \
  291. "run boot"
  292. #undef CONFIG_EXTRA_ENV_SETTINGS
  293. #define CONFIG_EXTRA_ENV_SETTINGS "boot=zboot 03000000 0 04000000 ${filesize}"
  294. and change CONFIG_BOOTARGS value in configs/minnowmax_defconfig to::
  295. CONFIG_BOOTARGS="root=/dev/sda2 ro"
  296. Test with SeaBIOS
  297. -----------------
  298. `SeaBIOS`_ is an open source implementation of a 16-bit x86 BIOS. It can run
  299. in an emulator or natively on x86 hardware with the use of U-Boot. With its
  300. help, we can boot some OSes that require 16-bit BIOS services like Windows/DOS.
  301. As U-Boot, we have to manually create a table where SeaBIOS gets various system
  302. information (eg: E820) from. The table unfortunately has to follow the coreboot
  303. table format as SeaBIOS currently supports booting as a coreboot payload.
  304. To support loading SeaBIOS, U-Boot should be built with CONFIG_SEABIOS on.
  305. Booting SeaBIOS is done via U-Boot's bootelf command, like below::
  306. => tftp bios.bin.elf;bootelf
  307. Using e1000#0 device
  308. TFTP from server 10.10.0.100; our IP address is 10.10.0.108
  309. ...
  310. Bytes transferred = 122124 (1dd0c hex)
  311. ## Starting application at 0x000ff06e ...
  312. SeaBIOS (version rel-1.9.0)
  313. ...
  314. bios.bin.elf is the SeaBIOS image built from SeaBIOS source tree.
  315. Make sure it is built as follows::
  316. $ make menuconfig
  317. Inside the "General Features" menu, select "Build for coreboot" as the
  318. "Build Target". Inside the "Debugging" menu, turn on "Serial port debugging"
  319. so that we can see something as soon as SeaBIOS boots. Leave other options
  320. as in their default state. Then::
  321. $ make
  322. ...
  323. Total size: 121888 Fixed: 66496 Free: 9184 (used 93.0% of 128KiB rom)
  324. Creating out/bios.bin.elf
  325. Currently this is tested on QEMU x86 target with U-Boot chain-loading SeaBIOS
  326. to install/boot a Windows XP OS (below for example command to install Windows).
  327. .. code-block:: none
  328. # Create a 10G disk.img as the virtual hard disk
  329. $ qemu-img create -f qcow2 disk.img 10G
  330. # Install a Windows XP OS from an ISO image 'winxp.iso'
  331. $ qemu-system-i386 -serial stdio -bios u-boot.rom -hda disk.img -cdrom winxp.iso -smp 2 -m 512
  332. # Boot a Windows XP OS installed on the virutal hard disk
  333. $ qemu-system-i386 -serial stdio -bios u-boot.rom -hda disk.img -smp 2 -m 512
  334. This is also tested on Intel Crown Bay board with a PCIe graphics card, booting
  335. SeaBIOS then chain-loading a GRUB on a USB drive, then Linux kernel finally.
  336. If you are using Intel Integrated Graphics Device (IGD) as the primary display
  337. device on your board, SeaBIOS needs to be patched manually to get its VGA ROM
  338. loaded and run by SeaBIOS. SeaBIOS locates VGA ROM via the PCI expansion ROM
  339. register, but IGD device does not have its VGA ROM mapped by this register.
  340. Its VGA ROM is packaged as part of u-boot.rom at a configurable flash address
  341. which is unknown to SeaBIOS. An example patch is needed for SeaBIOS below:
  342. .. code-block:: none
  343. diff --git a/src/optionroms.c b/src/optionroms.c
  344. index 65f7fe0..c7b6f5e 100644
  345. --- a/src/optionroms.c
  346. +++ b/src/optionroms.c
  347. @@ -324,6 +324,8 @@ init_pcirom(struct pci_device *pci, int isvga, u64 *sources)
  348. rom = deploy_romfile(file);
  349. else if (RunPCIroms > 1 || (RunPCIroms == 1 && isvga))
  350. rom = map_pcirom(pci);
  351. + if (pci->bdf == pci_to_bdf(0, 2, 0))
  352. + rom = (struct rom_header *)0xfff90000;
  353. if (! rom)
  354. // No ROM present.
  355. return;
  356. Note: the patch above expects IGD device is at PCI b.d.f 0.2.0 and its VGA ROM
  357. is at 0xfff90000 which corresponds to CONFIG_VGA_BIOS_ADDR on Minnowboard MAX.
  358. Change these two accordingly if this is not the case on your board.
  359. Development Flow
  360. ----------------
  361. These notes are for those who want to port U-Boot to a new x86 platform.
  362. Since x86 CPUs boot from SPI flash, a SPI flash emulator is a good investment.
  363. The Dediprog em100 can be used on Linux.
  364. The em100 tool is available here: http://review.coreboot.org/p/em100.git
  365. On Minnowboard Max the following command line can be used::
  366. sudo em100 -s -p LOW -d u-boot.rom -c W25Q64DW -r
  367. A suitable clip for connecting over the SPI flash chip is here:
  368. http://www.dediprog.com/pd/programmer-accessories/EM-TC-8.
  369. This allows you to override the SPI flash contents for development purposes.
  370. Typically you can write to the em100 in around 1200ms, considerably faster
  371. than programming the real flash device each time. The only important
  372. limitation of the em100 is that it only supports SPI bus speeds up to 20MHz.
  373. This means that images must be set to boot with that speed. This is an
  374. Intel-specific feature - e.g. tools/ifttool has an option to set the SPI
  375. speed in the SPI descriptor region.
  376. If your chip/board uses an Intel Firmware Support Package (FSP) it is fairly
  377. easy to fit it in. You can follow the Minnowboard Max implementation, for
  378. example. Hopefully you will just need to create new files similar to those
  379. in arch/x86/cpu/baytrail which provide Bay Trail support.
  380. If you are not using an FSP you have more freedom and more responsibility.
  381. The ivybridge support works this way, although it still uses a ROM for
  382. graphics and still has binary blobs containing Intel code. You should aim to
  383. support all important peripherals on your platform including video and storage.
  384. Use the device tree for configuration where possible.
  385. For the microcode you can create a suitable device tree file using the
  386. microcode tool::
  387. ./tools/microcode-tool -d microcode.dat -m <model> create
  388. or if you only have header files and not the full Intel microcode.dat database::
  389. ./tools/microcode-tool -H BAY_TRAIL_FSP_KIT/Microcode/M0130673322.h \
  390. -H BAY_TRAIL_FSP_KIT/Microcode/M0130679901.h -m all create
  391. These are written to arch/x86/dts/microcode/ by default.
  392. Note that it is possible to just add the micrcode for your CPU if you know its
  393. model. U-Boot prints this information when it starts::
  394. CPU: x86_64, vendor Intel, device 30673h
  395. so here we can use the M0130673322 file.
  396. If you platform can display POST codes on two little 7-segment displays on
  397. the board, then you can use post_code() calls from C or assembler to monitor
  398. boot progress. This can be good for debugging.
  399. If not, you can try to get serial working as early as possible. The early
  400. debug serial port may be useful here. See setup_internal_uart() for an example.
  401. During the U-Boot porting, one of the important steps is to write correct PIRQ
  402. routing information in the board device tree. Without it, device drivers in the
  403. Linux kernel won't function correctly due to interrupt is not working. Please
  404. refer to U-Boot `doc <doc/device-tree-bindings/misc/intel,irq-router.txt>`_ for
  405. the device tree bindings of Intel interrupt router. Here we have more details
  406. on the intel,pirq-routing property below.
  407. .. code-block:: none
  408. intel,pirq-routing = <
  409. PCI_BDF(0, 2, 0) INTA PIRQA
  410. ...
  411. >;
  412. As you see each entry has 3 cells. For the first one, we need describe all pci
  413. devices mounted on the board. For SoC devices, normally there is a chapter on
  414. the chipset datasheet which lists all the available PCI devices. For example on
  415. Bay Trail, this is chapter 4.3 (PCI configuration space). For the second one, we
  416. can get the interrupt pin either from datasheet or hardware via U-Boot shell.
  417. The reliable source is the hardware as sometimes chipset datasheet is not 100%
  418. up-to-date. Type 'pci header' plus the device's pci bus/device/function number
  419. from U-Boot shell below::
  420. => pci header 0.1e.1
  421. vendor ID = 0x8086
  422. device ID = 0x0f08
  423. ...
  424. interrupt line = 0x09
  425. interrupt pin = 0x04
  426. ...
  427. It shows this PCI device is using INTD pin as it reports 4 in the interrupt pin
  428. register. Repeat this until you get interrupt pins for all the devices. The last
  429. cell is the PIRQ line which a particular interrupt pin is mapped to. On Intel
  430. chipset, the power-up default mapping is INTA/B/C/D maps to PIRQA/B/C/D. This
  431. can be changed by registers in LPC bridge. So far Intel FSP does not touch those
  432. registers so we can write down the PIRQ according to the default mapping rule.
  433. Once we get the PIRQ routing information in the device tree, the interrupt
  434. allocation and assignment will be done by U-Boot automatically. Now you can
  435. enable CONFIG_GENERATE_PIRQ_TABLE for testing Linux kernel using i8259 PIC and
  436. CONFIG_GENERATE_MP_TABLE for testing Linux kernel using local APIC and I/O APIC.
  437. This script might be useful. If you feed it the output of 'pci long' from
  438. U-Boot then it will generate a device tree fragment with the interrupt
  439. configuration for each device (note it needs gawk 4.0.0)::
  440. $ cat console_output |awk '/PCI/ {device=$4} /interrupt line/ {line=$4} \
  441. /interrupt pin/ {pin = $4; if (pin != "0x00" && pin != "0xff") \
  442. {patsplit(device, bdf, "[0-9a-f]+"); \
  443. printf "PCI_BDF(%d, %d, %d) INT%c PIRQ%c\n", strtonum("0x" bdf[1]), \
  444. strtonum("0x" bdf[2]), bdf[3], strtonum(pin) + 64, 64 + strtonum(pin)}}'
  445. Example output::
  446. PCI_BDF(0, 2, 0) INTA PIRQA
  447. PCI_BDF(0, 3, 0) INTA PIRQA
  448. ...
  449. Porting Hints
  450. -------------
  451. Quark-specific considerations
  452. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  453. To port U-Boot to other boards based on the Intel Quark SoC, a few things need
  454. to be taken care of. The first important part is the Memory Reference Code (MRC)
  455. parameters. Quark MRC supports memory-down configuration only. All these MRC
  456. parameters are supplied via the board device tree. To get started, first copy
  457. the MRC section of arch/x86/dts/galileo.dts to your board's device tree, then
  458. change these values by consulting board manuals or your hardware vendor.
  459. Available MRC parameter values are listed in include/dt-bindings/mrc/quark.h.
  460. The other tricky part is with PCIe. Quark SoC integrates two PCIe root ports,
  461. but by default they are held in reset after power on. In U-Boot, PCIe
  462. initialization is properly handled as per Quark's firmware writer guide.
  463. In your board support codes, you need provide two routines to aid PCIe
  464. initialization, which are board_assert_perst() and board_deassert_perst().
  465. The two routines need implement a board-specific mechanism to assert/deassert
  466. PCIe PERST# pin. Care must be taken that in those routines that any APIs that
  467. may trigger PCI enumeration process are strictly forbidden, as any access to
  468. PCIe root port's configuration registers will cause system hang while it is
  469. held in reset. For more details, check how they are implemented by the Intel
  470. Galileo board support codes in board/intel/galileo/galileo.c.
  471. coreboot
  472. ^^^^^^^^
  473. See scripts/coreboot.sed which can assist with porting coreboot code into
  474. U-Boot drivers. It will not resolve all build errors, but will perform common
  475. transformations. Remember to add attribution to coreboot for new files added
  476. to U-Boot. This should go at the top of each file and list the coreboot
  477. filename where the code originated.
  478. Debugging ACPI issues with Windows
  479. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  480. Windows might cache system information and only detect ACPI changes if you
  481. modify the ACPI table versions. So tweak them liberally when debugging ACPI
  482. issues with Windows.
  483. ACPI Support Status
  484. -------------------
  485. Advanced Configuration and Power Interface (`ACPI`_) aims to establish
  486. industry-standard interfaces enabling OS-directed configuration, power
  487. management, and thermal management of mobile, desktop, and server platforms.
  488. Linux can boot without ACPI with "acpi=off" command line parameter, but
  489. with ACPI the kernel gains the capabilities to handle power management.
  490. For Windows, ACPI is a must-have firmware feature since Windows Vista.
  491. CONFIG_GENERATE_ACPI_TABLE is the config option to turn on ACPI support in
  492. U-Boot. This requires Intel ACPI compiler to be installed on your host to
  493. compile ACPI DSDT table written in ASL format to AML format. You can get
  494. the compiler via "apt-get install iasl" if you are on Ubuntu or download
  495. the source from https://www.acpica.org/downloads to compile one by yourself.
  496. Current ACPI support in U-Boot is basically complete. More optional features
  497. can be added in the future. The status as of today is:
  498. * Support generating RSDT, XSDT, FACS, FADT, MADT, MCFG tables.
  499. * Support one static DSDT table only, compiled by Intel ACPI compiler.
  500. * Support S0/S3/S4/S5, reboot and shutdown from OS.
  501. * Support booting a pre-installed Ubuntu distribution via 'zboot' command.
  502. * Support installing and booting Ubuntu 14.04 (or above) from U-Boot with
  503. the help of SeaBIOS using legacy interface (non-UEFI mode).
  504. * Support installing and booting Windows 8.1/10 from U-Boot with the help
  505. of SeaBIOS using legacy interface (non-UEFI mode).
  506. * Support ACPI interrupts with SCI only.
  507. Features that are optional:
  508. * Dynamic AML bytecodes insertion at run-time. We may need this to support
  509. SSDT table generation and DSDT fix up.
  510. * SMI support. Since U-Boot is a modern bootloader, we don't want to bring
  511. those legacy stuff into U-Boot. ACPI spec allows a system that does not
  512. support SMI (a legacy-free system).
  513. ACPI was initially enabled on BayTrail based boards. Testing was done by booting
  514. a pre-installed Ubuntu 14.04 from a SATA drive. Installing Ubuntu 14.04 and
  515. Windows 8.1/10 to a SATA drive and booting from there is also tested. Most
  516. devices seem to work correctly and the board can respond a reboot/shutdown
  517. command from the OS.
  518. For other platform boards, ACPI support status can be checked by examining their
  519. board defconfig files to see if CONFIG_GENERATE_ACPI_TABLE is set to y.
  520. The S3 sleeping state is a low wake latency sleeping state defined by ACPI
  521. spec where all system context is lost except system memory. To test S3 resume
  522. with a Linux kernel, simply run "echo mem > /sys/power/state" and kernel will
  523. put the board to S3 state where the power is off. So when the power button is
  524. pressed again, U-Boot runs as it does in cold boot and detects the sleeping
  525. state via ACPI register to see if it is S3, if yes it means we are waking up.
  526. U-Boot is responsible for restoring the machine state as it is before sleep.
  527. When everything is done, U-Boot finds out the wakeup vector provided by OSes
  528. and jump there. To determine whether ACPI S3 resume is supported, check to
  529. see if CONFIG_HAVE_ACPI_RESUME is set for that specific board.
  530. Note for testing S3 resume with Windows, correct graphics driver must be
  531. installed for your platform, otherwise you won't find "Sleep" option in
  532. the "Power" submenu from the Windows start menu.
  533. EFI Support
  534. -----------
  535. U-Boot supports booting as a 32-bit or 64-bit EFI payload, e.g. with UEFI.
  536. This is enabled with CONFIG_EFI_STUB to boot from both 32-bit and 64-bit
  537. UEFI BIOS. U-Boot can also run as an EFI application, with CONFIG_EFI_APP.
  538. The CONFIG_EFI_LOADER option, where U-Boot provides an EFI environment to
  539. the kernel (i.e. replaces UEFI completely but provides the same EFI run-time
  540. services) is supported too. For example, we can even use 'bootefi' command
  541. to load a 'u-boot-payload.efi', see below test logs on QEMU.
  542. .. code-block:: none
  543. => load ide 0 3000000 u-boot-payload.efi
  544. 489787 bytes read in 138 ms (3.4 MiB/s)
  545. => bootefi 3000000
  546. Scanning disk ide.blk#0...
  547. Found 2 disks
  548. WARNING: booting without device tree
  549. ## Starting EFI application at 03000000 ...
  550. U-Boot EFI Payload
  551. U-Boot 2018.07-rc2 (Jun 23 2018 - 17:12:58 +0800)
  552. CPU: x86_64, vendor AMD, device 663h
  553. DRAM: 2 GiB
  554. MMC:
  555. Video: 1024x768x32
  556. Model: EFI x86 Payload
  557. Net: e1000: 52:54:00:12:34:56
  558. Warning: e1000#0 using MAC address from ROM
  559. eth0: e1000#0
  560. No controllers found
  561. Hit any key to stop autoboot: 0
  562. See :doc:`../uefi/u-boot_on_efi` and :doc:`../uefi/uefi` for details of
  563. EFI support in U-Boot.
  564. Chain-loading
  565. -------------
  566. U-Boot can be chain-loaded from another bootloader, such as coreboot or
  567. Slim Bootloader. Typically this is done by building for targets 'coreboot' or
  568. 'slimbootloader'.
  569. For example, at present we have a 'coreboot' target but this runs very
  570. different code from the bare-metal targets, such as coral. There is very little
  571. in common between them.
  572. It is useful to be able to boot the same U-Boot on a device, with or without a
  573. first-stage bootloader. For example, with chromebook_coral, it is helpful for
  574. testing to be able to boot the same U-Boot (complete with FSP) on bare metal
  575. and from coreboot. It allows checking of things like CPU speed, comparing
  576. registers, ACPI tables and the like.
  577. To do this you can use ll_boot_init() in appropriate places to skip init that
  578. has already been done by the previous stage. This works by setting a
  579. GD_FLG_NO_LL_INIT flag when U-Boot detects that it is running from another
  580. bootloader.
  581. With this feature, you can build a bare-metal target and boot it from
  582. coreboot, for example.
  583. Note that this is a development feature only. It is not intended for use in
  584. production environments. Also it is not currently part of the automated tests
  585. so may break in the future.
  586. SMBIOS tables
  587. -------------
  588. To generate SMBIOS tables in U-Boot, for use by the OS, enable the
  589. CONFIG_GENERATE_SMBIOS_TABLE option. The easiest way to provide the values to
  590. use is via the device tree. For details see
  591. device-tree-bindings/sysinfo/smbios.txt
  592. TODO List
  593. ---------
  594. - Audio
  595. - Chrome OS verified boot
  596. .. _coreboot: http://www.coreboot.org
  597. .. _QEMU: http://www.qemu.org
  598. .. _microcode: http://en.wikipedia.org/wiki/Microcode
  599. .. _SFI: http://simplefirmware.org
  600. .. _MP: http://www.intel.com/design/archives/processors/pro/docs/242016.htm
  601. .. _here: https://en.wikipedia.org/wiki/GUID_Partition_Table
  602. .. _this: http://events.linuxfoundation.org/sites/events/files/slides/chromeos_and_diy_vboot_0.pdf
  603. .. _that: http://events.linuxfoundation.org/sites/events/files/slides/elce-2014.pdf
  604. .. _SeaBIOS: http://www.seabios.org/SeaBIOS
  605. .. _ACPI: http://www.acpi.info