blob: 36aaef011de9956dc6f3a6921024f8458b8b1448 [file] [log] [blame]
Bin Meng5dad97e2014-12-17 15:50:48 +08001#
2# Copyright (C) 2014, Simon Glass <sjg@chromium.org>
3# Copyright (C) 2014, Bin Meng <bmeng.cn@gmail.com>
4#
5# SPDX-License-Identifier: GPL-2.0+
6#
7
8U-Boot on x86
9=============
10
11This document describes the information about U-Boot running on x86 targets,
12including supported boards, build instructions, todo list, etc.
13
14Status
15------
16U-Boot supports running as a coreboot [1] payload on x86. So far only Link
Bin Meng1ae5b782015-05-07 21:34:12 +080017(Chromebook Pixel) and QEMU [2] x86 targets have been tested, but it should
18work with minimal adjustments on other x86 boards since coreboot deals with
19most of the low-level details.
Bin Meng5dad97e2014-12-17 15:50:48 +080020
Stoppa, Igor28a85362015-08-13 16:43:35 +030021U-Boot also supports booting directly from x86 reset vector, without coreboot.
22In this case, known as bare mode, from the fact that it runs on the
23'bare metal', U-Boot acts like a BIOS replacement. Currently Link, QEMU x86
24targets and all Intel boards support running U-Boot 'bare metal'.
Bin Meng5dad97e2014-12-17 15:50:48 +080025
Simon Glass3a1a18f2015-01-27 22:13:47 -070026As for loading an OS, U-Boot supports directly booting a 32-bit or 64-bit
27Linux kernel as part of a FIT image. It also supports a compressed zImage.
Bin Meng3619e942015-10-07 20:19:20 -070028U-Boot supports loading an x86 VxWorks kernel. Please check README.vxworks
29for more details.
Bin Meng5dad97e2014-12-17 15:50:48 +080030
Stoppa, Igor28a85362015-08-13 16:43:35 +030031Build Instructions for U-Boot as coreboot payload
32-------------------------------------------------
Bin Meng5dad97e2014-12-17 15:50:48 +080033Building U-Boot as a coreboot payload is just like building U-Boot for targets
34on other architectures, like below:
35
36$ make coreboot-x86_defconfig
37$ make all
38
Bin Meng1ae5b782015-05-07 21:34:12 +080039Note this default configuration will build a U-Boot payload for the QEMU board.
Bin Meng617b8672015-01-06 22:14:24 +080040To build a coreboot payload against another board, you can change the build
41configuration during the 'make menuconfig' process.
42
43x86 architecture --->
44 ...
Bin Meng1ae5b782015-05-07 21:34:12 +080045 (qemu-x86) Board configuration file
Bin Meng683b09d2015-06-03 09:20:04 +080046 (qemu-x86_i440fx) Board Device Tree Source (dts) file
Bin Meng1ae5b782015-05-07 21:34:12 +080047 (0x01920000) Board specific Cache-As-RAM (CAR) address
Bin Meng617b8672015-01-06 22:14:24 +080048 (0x4000) Board specific Cache-As-RAM (CAR) size
49
50Change the 'Board configuration file' and 'Board Device Tree Source (dts) file'
51to point to a new board. You can also change the Cache-As-RAM (CAR) related
52settings here if the default values do not fit your new board.
53
Stoppa, Igor28a85362015-08-13 16:43:35 +030054Build Instructions for U-Boot as BIOS replacement (bare mode)
55-------------------------------------------------------------
Simon Glass3a1a18f2015-01-27 22:13:47 -070056Building a ROM version of U-Boot (hereafter referred to as u-boot.rom) is a
Bin Meng5dad97e2014-12-17 15:50:48 +080057little bit tricky, as generally it requires several binary blobs which are not
58shipped in the U-Boot source tree. Due to this reason, the u-boot.rom build is
59not turned on by default in the U-Boot source tree. Firstly, you need turn it
Simon Glasseea0f112015-01-27 22:13:32 -070060on by enabling the ROM build:
Bin Meng5dad97e2014-12-17 15:50:48 +080061
Simon Glasseea0f112015-01-27 22:13:32 -070062$ export BUILD_ROM=y
63
64This tells the Makefile to build u-boot.rom as a target.
Bin Meng5dad97e2014-12-17 15:50:48 +080065
Stoppa, Igor28a85362015-08-13 16:43:35 +030066---
67
68Chromebook Link specific instructions for bare mode:
Bin Meng5dad97e2014-12-17 15:50:48 +080069
70First, you need the following binary blobs:
71
72* descriptor.bin - Intel flash descriptor
73* me.bin - Intel Management Engine
74* mrc.bin - Memory Reference Code, which sets up SDRAM
75* video ROM - sets up the display
76
77You can get these binary blobs by:
78
79$ git clone http://review.coreboot.org/p/blobs.git
80$ cd blobs
81
82Find the following files:
83
84* ./mainboard/google/link/descriptor.bin
85* ./mainboard/google/link/me.bin
Simon Glass8712af92015-04-19 22:05:37 -060086* ./northbridge/intel/sandybridge/systemagent-r6.bin
Bin Meng5dad97e2014-12-17 15:50:48 +080087
88The 3rd one should be renamed to mrc.bin.
Bin Meng786a08e2015-07-06 16:31:33 +080089As for the video ROM, you can get it here [3] and rename it to vga.bin.
Bin Meng5dad97e2014-12-17 15:50:48 +080090Make sure all these binary blobs are put in the board directory.
91
92Now you can build U-Boot and obtain u-boot.rom:
93
94$ make chromebook_link_defconfig
95$ make all
96
Stoppa, Igor28a85362015-08-13 16:43:35 +030097---
98
99Intel Crown Bay specific instructions for bare mode:
Bin Meng5dad97e2014-12-17 15:50:48 +0800100
Bin Meng1ae5b782015-05-07 21:34:12 +0800101U-Boot support of Intel Crown Bay board [4] relies on a binary blob called
102Firmware Support Package [5] to perform all the necessary initialization steps
Bin Meng5dad97e2014-12-17 15:50:48 +0800103as documented in the BIOS Writer Guide, including initialization of the CPU,
104memory controller, chipset and certain bus interfaces.
105
106Download the Intel FSP for Atom E6xx series and Platform Controller Hub EG20T,
107install it on your host and locate the FSP binary blob. Note this platform
108also requires a Chipset Micro Code (CMC) state machine binary to be present in
109the SPI flash where u-boot.rom resides, and this CMC binary blob can be found
110in this FSP package too.
111
112* ./FSP/QUEENSBAY_FSP_GOLD_001_20-DECEMBER-2013.fd
113* ./Microcode/C0_22211.BIN
114
115Rename the first one to fsp.bin and second one to cmc.bin and put them in the
116board directory.
117
Bin Meng83d97122015-03-05 11:21:03 +0800118Note the FSP release version 001 has a bug which could cause random endless
119loop during the FspInit call. This bug was published by Intel although Intel
120did not describe any details. We need manually apply the patch to the FSP
121binary using any hex editor (eg: bvi). Go to the offset 0x1fcd8 of the FSP
122binary, change the following five bytes values from orginally E8 42 FF FF FF
123to B8 00 80 0B 00.
124
Bin Meng7aaff9b2015-07-06 16:31:35 +0800125As for the video ROM, you need manually extract it from the Intel provided
126BIOS for Crown Bay here [6], using the AMI MMTool [7]. Check PCI option ROM
127ID 8086:4108, extract and save it as vga.bin in the board directory.
128
Bin Meng617b8672015-01-06 22:14:24 +0800129Now you can build U-Boot and obtain u-boot.rom
Bin Meng5dad97e2014-12-17 15:50:48 +0800130
131$ make crownbay_defconfig
132$ make all
133
Stoppa, Igor28a85362015-08-13 16:43:35 +0300134---
135
136Intel Minnowboard Max instructions for bare mode:
Simon Glass3a1a18f2015-01-27 22:13:47 -0700137
138This uses as FSP as with Crown Bay, except it is for the Atom E3800 series.
139Download this and get the .fd file (BAYTRAIL_FSP_GOLD_003_16-SEP-2014.fd at
140the time of writing). Put it in the board directory:
141board/intel/minnowmax/fsp.bin
142
143Obtain the VGA RAM (Vga.dat at the time of writing) and put it into the same
144directory: board/intel/minnowmax/vga.bin
145
Simon Glass68522482015-04-25 11:46:43 -0600146You still need two more binary blobs. The first comes from the original
147firmware image available from:
148
149http://firmware.intel.com/sites/default/files/2014-WW42.4-MinnowBoardMax.73-64-bit.bin_Release.zip
150
151Unzip it:
152
153 $ unzip 2014-WW42.4-MinnowBoardMax.73-64-bit.bin_Release.zip
Simon Glass3a1a18f2015-01-27 22:13:47 -0700154
155Use ifdtool in the U-Boot tools directory to extract the images from that
156file, for example:
157
Simon Glass68522482015-04-25 11:46:43 -0600158 $ ./tools/ifdtool -x MNW2MAX1.X64.0073.R02.1409160934.bin
159
160This will provide the descriptor file - copy this into the correct place:
161
162 $ cp flashregion_0_flashdescriptor.bin board/intel/minnowmax/descriptor.bin
163
164Then do the same with the sample SPI image provided in the FSP (SPI.bin at
165the time of writing) to obtain the last image. Note that this will also
166produce a flash descriptor file, but it does not seem to work, probably
167because it is not designed for the Minnowmax. That is why you need to get
168the flash descriptor from the original firmware as above.
169
Simon Glass3a1a18f2015-01-27 22:13:47 -0700170 $ ./tools/ifdtool -x BayleyBay/SPI.bin
171 $ cp flashregion_2_intel_me.bin board/intel/minnowmax/me.bin
Simon Glass3a1a18f2015-01-27 22:13:47 -0700172
173Now you can build U-Boot and obtain u-boot.rom
174
175$ make minnowmax_defconfig
176$ make all
177
Simon Glassdf898672015-07-03 18:28:28 -0600178Checksums are as follows (but note that newer versions will invalidate this):
179
180$ md5sum -b board/intel/minnowmax/*.bin
181ffda9a3b94df5b74323afb328d51e6b4 board/intel/minnowmax/descriptor.bin
18269f65b9a580246291d20d08cbef9d7c5 board/intel/minnowmax/fsp.bin
183894a97d371544ec21de9c3e8e1716c4b board/intel/minnowmax/me.bin
184a2588537da387da592a27219d56e9962 board/intel/minnowmax/vga.bin
185
Simon Glass537ccba2015-07-03 18:28:24 -0600186The ROM image is broken up into these parts:
187
188Offset Description Controlling config
189------------------------------------------------------------
190000000 descriptor.bin Hard-coded to 0 in ifdtool
191001000 me.bin Set by the descriptor
192500000 <spare>
Bin Meng638a0582015-10-11 21:37:44 -07001936f0000 MRC cache CONFIG_ENABLE_MRC_CACHE
Simon Glass537ccba2015-07-03 18:28:24 -0600194700000 u-boot-dtb.bin CONFIG_SYS_TEXT_BASE
Bin Meng7f72cdf2015-08-27 08:38:16 -0700195790000 vga.bin CONFIG_VGA_BIOS_ADDR
Simon Glass537ccba2015-07-03 18:28:24 -06001967c0000 fsp.bin CONFIG_FSP_ADDR
1977f8000 <spare> (depends on size of fsp.bin)
1987fe000 Environment CONFIG_ENV_OFFSET
1997ff800 U-Boot 16-bit boot CONFIG_SYS_X86_START16
200
201Overall ROM image size is controlled by CONFIG_ROM_SIZE.
202
Stoppa, Igor28a85362015-08-13 16:43:35 +0300203---
Simon Glass537ccba2015-07-03 18:28:24 -0600204
Stoppa, Igor28a85362015-08-13 16:43:35 +0300205Intel Galileo instructions for bare mode:
Bin Meng67582c02015-02-04 16:26:14 +0800206
207Only one binary blob is needed for Remote Management Unit (RMU) within Intel
208Quark SoC. Not like FSP, U-Boot does not call into the binary. The binary is
209needed by the Quark SoC itself.
210
211You can get the binary blob from Quark Board Support Package from Intel website:
212
213* ./QuarkSocPkg/QuarkNorthCluster/Binary/QuarkMicrocode/RMU.bin
214
215Rename the file and put it to the board directory by:
216
217 $ cp RMU.bin board/intel/galileo/rmu.bin
218
219Now you can build U-Boot and obtain u-boot.rom
220
221$ make galileo_defconfig
222$ make all
Simon Glass3a1a18f2015-01-27 22:13:47 -0700223
Bin Meng1ae5b782015-05-07 21:34:12 +0800224QEMU x86 target instructions:
225
226To build u-boot.rom for QEMU x86 targets, just simply run
227
228$ make qemu-x86_defconfig
229$ make all
230
Bin Meng683b09d2015-06-03 09:20:04 +0800231Note this default configuration will build a U-Boot for the QEMU x86 i440FX
232board. To build a U-Boot against QEMU x86 Q35 board, you can change the build
233configuration during the 'make menuconfig' process like below:
234
235Device Tree Control --->
236 ...
237 (qemu-x86_q35) Default Device Tree for DT control
238
Bin Meng617b8672015-01-06 22:14:24 +0800239Test with coreboot
240------------------
241For testing U-Boot as the coreboot payload, there are things that need be paid
242attention to. coreboot supports loading an ELF executable and a 32-bit plain
243binary, as well as other supported payloads. With the default configuration,
244U-Boot is set up to use a separate Device Tree Blob (dtb). As of today, the
245generated u-boot-dtb.bin needs to be packaged by the cbfstool utility (a tool
246provided by coreboot) manually as coreboot's 'make menuconfig' does not provide
247this capability yet. The command is as follows:
248
249# in the coreboot root directory
250$ ./build/util/cbfstool/cbfstool build/coreboot.rom add-flat-binary \
Bin Meng330728d2015-08-13 00:29:07 -0700251 -f u-boot-dtb.bin -n fallback/payload -c lzma -l 0x1110000 -e 0x1110000
Bin Meng617b8672015-01-06 22:14:24 +0800252
Bin Meng330728d2015-08-13 00:29:07 -0700253Make sure 0x1110000 matches CONFIG_SYS_TEXT_BASE, which is the symbol address
254of _x86boot_start (in arch/x86/cpu/start.S).
Bin Meng617b8672015-01-06 22:14:24 +0800255
256If you want to use ELF as the coreboot payload, change U-Boot configuration to
Simon Glasseea0f112015-01-27 22:13:32 -0700257use CONFIG_OF_EMBED instead of CONFIG_OF_SEPARATE.
Bin Meng617b8672015-01-06 22:14:24 +0800258
Simon Glass3a1a18f2015-01-27 22:13:47 -0700259To enable video you must enable these options in coreboot:
260
261 - Set framebuffer graphics resolution (1280x1024 32k-color (1:5:5))
262 - Keep VESA framebuffer
263
264At present it seems that for Minnowboard Max, coreboot does not pass through
265the video information correctly (it always says the resolution is 0x0). This
266works correctly for link though.
267
Stoppa, Igor28a85362015-08-13 16:43:35 +0300268Test with QEMU for bare mode
269----------------------------
Bin Meng1ae5b782015-05-07 21:34:12 +0800270QEMU is a fancy emulator that can enable us to test U-Boot without access to
Bin Meng9c4f5412015-05-11 07:36:30 +0800271a real x86 board. Please make sure your QEMU version is 2.3.0 or above test
272U-Boot. To launch QEMU with u-boot.rom, call QEMU as follows:
Bin Meng1ae5b782015-05-07 21:34:12 +0800273
274$ qemu-system-i386 -nographic -bios path/to/u-boot.rom
275
276This will instantiate an emulated x86 board with i440FX and PIIX chipset. QEMU
277also supports emulating an x86 board with Q35 and ICH9 based chipset, which is
278also supported by U-Boot. To instantiate such a machine, call QEMU with:
279
280$ qemu-system-i386 -nographic -bios path/to/u-boot.rom -M q35
281
282Note by default QEMU instantiated boards only have 128 MiB system memory. But
283it is enough to have U-Boot boot and function correctly. You can increase the
284system memory by pass '-m' parameter to QEMU if you want more memory:
285
286$ qemu-system-i386 -nographic -bios path/to/u-boot.rom -m 1024
287
288This creates a board with 1 GiB system memory. Currently U-Boot for QEMU only
289supports 3 GiB maximum system memory and reserves the last 1 GiB address space
290for PCI device memory-mapped I/O and other stuff, so the maximum value of '-m'
291would be 3072.
Simon Glass3a1a18f2015-01-27 22:13:47 -0700292
Bin Meng9c4f5412015-05-11 07:36:30 +0800293QEMU emulates a graphic card which U-Boot supports. Removing '-nographic' will
294show QEMU's VGA console window. Note this will disable QEMU's serial output.
295If you want to check both consoles, use '-serial stdio'.
296
Bin Menga2eb65f2015-07-27 19:16:08 +0800297Multicore is also supported by QEMU via '-smp n' where n is the number of cores
Miao Yan5c2ed612016-01-07 01:32:06 -0800298to instantiate. Note, the maximum supported CPU number in QEMU is 255.
299
300The fw_cfg interface in QEMU also provides information about kernel data, initrd,
301command-line arguments and more. U-Boot supports directly accessing these informtion
302from fw_cfg interface, this saves the time of loading them from hard disk or
303network again, through emulated devices. To use it , simply providing them in
304QEMU command line:
305
306$ qemu-system-i386 -nographic -bios path/to/u-boot.rom -m 1024 -kernel /path/to/bzImage
307 -append 'root=/dev/ram console=ttyS0' -initrd /path/to/initrd -smp 8
308
309Note: -initrd and -smp are both optional
310
311Then start QEMU, in U-Boot command line use the following U-Boot command to setup kernel:
312
313 => qfw
314qfw - QEMU firmware interface
315
316Usage:
317qfw <command>
318 - list : print firmware(s) currently loaded
319 - cpus : print online cpu number
320 - load <kernel addr> <initrd addr> : load kernel and initrd (if any) and setup for zboot
321
322=> qfw load
323loading kernel to address 01000000 size 5d9d30 initrd 04000000 size 1b1ab50
324
325Here the kernel (bzImage) is loaded to 01000000 and initrd is to 04000000. Then, 'zboot'
326can be used to boot the kernel:
327
328=> zboot 02000000 - 04000000 1b1ab50
Bin Menga2eb65f2015-07-27 19:16:08 +0800329
Bin Meng5dad97e2014-12-17 15:50:48 +0800330CPU Microcode
331-------------
Bin Meng7aaff9b2015-07-06 16:31:35 +0800332Modern CPUs usually require a special bit stream called microcode [8] to be
Bin Meng5dad97e2014-12-17 15:50:48 +0800333loaded on the processor after power up in order to function properly. U-Boot
334has already integrated these as hex dumps in the source tree.
335
Bin Meng1281a1f2015-06-23 12:18:53 +0800336SMP Support
337-----------
338On a multicore system, U-Boot is executed on the bootstrap processor (BSP).
339Additional application processors (AP) can be brought up by U-Boot. In order to
340have an SMP kernel to discover all of the available processors, U-Boot needs to
341prepare configuration tables which contain the multi-CPUs information before
342loading the OS kernel. Currently U-Boot supports generating two types of tables
Bin Meng7aaff9b2015-07-06 16:31:35 +0800343for SMP, called Simple Firmware Interface (SFI) [9] and Multi-Processor (MP)
344[10] tables. The writing of these two tables are controlled by two Kconfig
345options GENERATE_SFI_TABLE and GENERATE_MP_TABLE.
Bin Meng1281a1f2015-06-23 12:18:53 +0800346
Bin Meng5dad97e2014-12-17 15:50:48 +0800347Driver Model
348------------
349x86 has been converted to use driver model for serial and GPIO.
350
351Device Tree
352-----------
353x86 uses device tree to configure the board thus requires CONFIG_OF_CONTROL to
Bin Meng617b8672015-01-06 22:14:24 +0800354be turned on. Not every device on the board is configured via device tree, but
Bin Meng5dad97e2014-12-17 15:50:48 +0800355more and more devices will be added as time goes by. Check out the directory
356arch/x86/dts/ for these device tree source files.
357
Simon Glasscb3b2e62015-01-01 16:18:15 -0700358Useful Commands
359---------------
Simon Glasscb3b2e62015-01-01 16:18:15 -0700360In keeping with the U-Boot philosophy of providing functions to check and
361adjust internal settings, there are several x86-specific commands that may be
362useful:
363
Bin Meng62716eb2015-10-10 01:47:58 -0700364fsp - Display information about Intel Firmware Support Package (FSP).
365 This is only available on platforms which use FSP, mostly Atom.
Simon Glasscb3b2e62015-01-01 16:18:15 -0700366iod - Display I/O memory
367iow - Write I/O memory
368mtrr - List and set the Memory Type Range Registers (MTRR). These are used to
369 tell the CPU whether memory is cacheable and if so the cache write
370 mode to use. U-Boot sets up some reasonable values but you can
371 adjust then with this command.
372
Simon Glass7bea5272015-07-27 15:47:31 -0600373Booting Ubuntu
374--------------
375As an example of how to set up your boot flow with U-Boot, here are
376instructions for starting Ubuntu from U-Boot. These instructions have been
377tested on Minnowboard MAX with a SATA driver but are equally applicable on
378other platforms and other media. There are really only four steps and its a
379very simple script, but a more detailed explanation is provided here for
380completeness.
381
382Note: It is possible to set up U-Boot to boot automatically using syslinux.
383It could also use the grub.cfg file (/efi/ubuntu/grub.cfg) to obtain the
384GUID. If you figure these out, please post patches to this README.
385
386Firstly, you will need Ubunutu installed on an available disk. It should be
387possible to make U-Boot start a USB start-up disk but for now let's assume
388that you used another boot loader to install Ubuntu.
389
390Use the U-Boot command line to find the UUID of the partition you want to
391boot. For example our disk is SCSI device 0:
392
393=> part list scsi 0
394
395Partition Map for SCSI device 0 -- Partition Type: EFI
396
397 Part Start LBA End LBA Name
398 Attributes
399 Type GUID
400 Partition GUID
401 1 0x00000800 0x001007ff ""
402 attrs: 0x0000000000000000
403 type: c12a7328-f81f-11d2-ba4b-00a0c93ec93b
404 guid: 9d02e8e4-4d59-408f-a9b0-fd497bc9291c
405 2 0x00100800 0x037d8fff ""
406 attrs: 0x0000000000000000
407 type: 0fc63daf-8483-4772-8e79-3d69d8477de4
408 guid: 965c59ee-1822-4326-90d2-b02446050059
409 3 0x037d9000 0x03ba27ff ""
410 attrs: 0x0000000000000000
411 type: 0657fd6d-a4ab-43c4-84e5-0933c84b4f4f
412 guid: 2c4282bd-1e82-4bcf-a5ff-51dedbf39f17
413 =>
414
415This shows that your SCSI disk has three partitions. The really long hex
416strings are called Globally Unique Identifiers (GUIDs). You can look up the
417'type' ones here [11]. On this disk the first partition is for EFI and is in
418VFAT format (DOS/Windows):
419
420 => fatls scsi 0:1
421 efi/
422
423 0 file(s), 1 dir(s)
424
425
426Partition 2 is 'Linux filesystem data' so that will be our root disk. It is
427in ext2 format:
428
429 => ext2ls scsi 0:2
430 <DIR> 4096 .
431 <DIR> 4096 ..
432 <DIR> 16384 lost+found
433 <DIR> 4096 boot
434 <DIR> 12288 etc
435 <DIR> 4096 media
436 <DIR> 4096 bin
437 <DIR> 4096 dev
438 <DIR> 4096 home
439 <DIR> 4096 lib
440 <DIR> 4096 lib64
441 <DIR> 4096 mnt
442 <DIR> 4096 opt
443 <DIR> 4096 proc
444 <DIR> 4096 root
445 <DIR> 4096 run
446 <DIR> 12288 sbin
447 <DIR> 4096 srv
448 <DIR> 4096 sys
449 <DIR> 4096 tmp
450 <DIR> 4096 usr
451 <DIR> 4096 var
452 <SYM> 33 initrd.img
453 <SYM> 30 vmlinuz
454 <DIR> 4096 cdrom
455 <SYM> 33 initrd.img.old
456 =>
457
458and if you look in the /boot directory you will see the kernel:
459
460 => ext2ls scsi 0:2 /boot
461 <DIR> 4096 .
462 <DIR> 4096 ..
463 <DIR> 4096 efi
464 <DIR> 4096 grub
465 3381262 System.map-3.13.0-32-generic
466 1162712 abi-3.13.0-32-generic
467 165611 config-3.13.0-32-generic
468 176500 memtest86+.bin
469 178176 memtest86+.elf
470 178680 memtest86+_multiboot.bin
471 5798112 vmlinuz-3.13.0-32-generic
472 165762 config-3.13.0-58-generic
473 1165129 abi-3.13.0-58-generic
474 5823136 vmlinuz-3.13.0-58-generic
475 19215259 initrd.img-3.13.0-58-generic
476 3391763 System.map-3.13.0-58-generic
477 5825048 vmlinuz-3.13.0-58-generic.efi.signed
478 28304443 initrd.img-3.13.0-32-generic
479 =>
480
481The 'vmlinuz' files contain a packaged Linux kernel. The format is a kind of
482self-extracting compressed file mixed with some 'setup' configuration data.
483Despite its size (uncompressed it is >10MB) this only includes a basic set of
484device drivers, enough to boot on most hardware types.
485
486The 'initrd' files contain a RAM disk. This is something that can be loaded
487into RAM and will appear to Linux like a disk. Ubuntu uses this to hold lots
488of drivers for whatever hardware you might have. It is loaded before the
489real root disk is accessed.
490
491The numbers after the end of each file are the version. Here it is Linux
492version 3.13. You can find the source code for this in the Linux tree with
493the tag v3.13. The '.0' allows for additional Linux releases to fix problems,
494but normally this is not needed. The '-58' is used by Ubuntu. Each time they
495release a new kernel they increment this number. New Ubuntu versions might
496include kernel patches to fix reported bugs. Stable kernels can exist for
497some years so this number can get quite high.
498
499The '.efi.signed' kernel is signed for EFI's secure boot. U-Boot has its own
500secure boot mechanism - see [12] [13] and cannot read .efi files at present.
501
502To boot Ubuntu from U-Boot the steps are as follows:
503
5041. Set up the boot arguments. Use the GUID for the partition you want to
505boot:
506
507 => setenv bootargs root=/dev/disk/by-partuuid/965c59ee-1822-4326-90d2-b02446050059 ro
508
509Here root= tells Linux the location of its root disk. The disk is specified
510by its GUID, using '/dev/disk/by-partuuid/', a Linux path to a 'directory'
511containing all the GUIDs Linux has found. When it starts up, there will be a
512file in that directory with this name in it. It is also possible to use a
513device name here, see later.
514
5152. Load the kernel. Since it is an ext2/4 filesystem we can do:
516
517 => ext2load scsi 0:2 03000000 /boot/vmlinuz-3.13.0-58-generic
518
519The address 30000000 is arbitrary, but there seem to be problems with using
520small addresses (sometimes Linux cannot find the ramdisk). This is 48MB into
521the start of RAM (which is at 0 on x86).
522
5233. Load the ramdisk (to 64MB):
524
525 => ext2load scsi 0:2 04000000 /boot/initrd.img-3.13.0-58-generic
526
5274. Start up the kernel. We need to know the size of the ramdisk, but can use
528a variable for that. U-Boot sets 'filesize' to the size of the last file it
529loaded.
530
531 => zboot 03000000 0 04000000 ${filesize}
532
533Type 'help zboot' if you want to see what the arguments are. U-Boot on x86 is
534quite verbose when it boots a kernel. You should see these messages from
535U-Boot:
536
537 Valid Boot Flag
538 Setup Size = 0x00004400
539 Magic signature found
540 Using boot protocol version 2.0c
541 Linux kernel version 3.13.0-58-generic (buildd@allspice) #97-Ubuntu SMP Wed Jul 8 02:56:15 UTC 2015
542 Building boot_params at 0x00090000
543 Loading bzImage at address 100000 (5805728 bytes)
544 Magic signature found
545 Initial RAM disk at linear address 0x04000000, size 19215259 bytes
546 Kernel command line: "console=ttyS0,115200 root=/dev/disk/by-partuuid/965c59ee-1822-4326-90d2-b02446050059 ro"
547
548 Starting kernel ...
549
550U-Boot prints out some bootstage timing. This is more useful if you put the
551above commands into a script since then it will be faster.
552
553 Timer summary in microseconds:
554 Mark Elapsed Stage
555 0 0 reset
556 241,535 241,535 board_init_r
557 2,421,611 2,180,076 id=64
558 2,421,790 179 id=65
559 2,428,215 6,425 main_loop
560 48,860,584 46,432,369 start_kernel
561
562 Accumulated time:
563 240,329 ahci
564 1,422,704 vesa display
565
566Now the kernel actually starts:
567
568 [ 0.000000] Initializing cgroup subsys cpuset
569 [ 0.000000] Initializing cgroup subsys cpu
570 [ 0.000000] Initializing cgroup subsys cpuacct
571 [ 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)
572 [ 0.000000] Command line: console=ttyS0,115200 root=/dev/disk/by-partuuid/965c59ee-1822-4326-90d2-b02446050059 ro
573
574It continues for a long time. Along the way you will see it pick up your
575ramdisk:
576
577 [ 0.000000] RAMDISK: [mem 0x04000000-0x05253fff]
578...
579 [ 0.788540] Trying to unpack rootfs image as initramfs...
580 [ 1.540111] Freeing initrd memory: 18768K (ffff880004000000 - ffff880005254000)
581...
582
583Later it actually starts using it:
584
585 Begin: Running /scripts/local-premount ... done.
586
587You should also see your boot disk turn up:
588
589 [ 4.357243] scsi 1:0:0:0: Direct-Access ATA ADATA SP310 5.2 PQ: 0 ANSI: 5
590 [ 4.366860] sd 1:0:0:0: [sda] 62533296 512-byte logical blocks: (32.0 GB/29.8 GiB)
591 [ 4.375677] sd 1:0:0:0: Attached scsi generic sg0 type 0
592 [ 4.381859] sd 1:0:0:0: [sda] Write Protect is off
593 [ 4.387452] sd 1:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
594 [ 4.399535] sda: sda1 sda2 sda3
595
596Linux has found the three partitions (sda1-3). Mercifully it doesn't print out
597the GUIDs. In step 1 above we could have used:
598
599 setenv bootargs root=/dev/sda2 ro
600
601instead of the GUID. However if you add another drive to your board the
602numbering may change whereas the GUIDs will not. So if your boot partition
603becomes sdb2, it will still boot. For embedded systems where you just want to
604boot the first disk, you have that option.
605
606The last thing you will see on the console is mention of plymouth (which
607displays the Ubuntu start-up screen) and a lot of 'Starting' messages:
608
609 * Starting Mount filesystems on boot [ OK ]
610
611After a pause you should see a login screen on your display and you are done.
612
613If you want to put this in a script you can use something like this:
614
615 setenv bootargs root=UUID=b2aaf743-0418-4d90-94cc-3e6108d7d968 ro
616 setenv boot zboot 03000000 0 04000000 \${filesize}
617 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"
618 saveenv
619
620The \ is to tell the shell not to evaluate ${filesize} as part of the setenv
621command.
622
623You will also need to add this to your board configuration file, e.g.
624include/configs/minnowmax.h:
625
626 #define CONFIG_BOOTDELAY 2
627
628Now when you reset your board it wait a few seconds (in case you want to
629interrupt) and then should boot straight into Ubuntu.
630
631You can also bake this behaviour into your build by hard-coding the
632environment variables if you add this to minnowmax.h:
633
634#undef CONFIG_BOOTARGS
635#undef CONFIG_BOOTCOMMAND
636
637#define CONFIG_BOOTARGS \
638 "root=/dev/sda2 ro"
639#define CONFIG_BOOTCOMMAND \
640 "ext2load scsi 0:2 03000000 /boot/vmlinuz-3.13.0-58-generic; " \
641 "ext2load scsi 0:2 04000000 /boot/initrd.img-3.13.0-58-generic; " \
642 "run boot"
643
644#undef CONFIG_EXTRA_ENV_SETTINGS
645#define CONFIG_EXTRA_ENV_SETTINGS "boot=zboot 03000000 0 04000000 ${filesize}"
646
647
Simon Glass00bdd952015-01-27 22:13:46 -0700648Development Flow
649----------------
Simon Glass00bdd952015-01-27 22:13:46 -0700650These notes are for those who want to port U-Boot to a new x86 platform.
651
652Since x86 CPUs boot from SPI flash, a SPI flash emulator is a good investment.
653The Dediprog em100 can be used on Linux. The em100 tool is available here:
654
655 http://review.coreboot.org/p/em100.git
656
657On Minnowboard Max the following command line can be used:
658
659 sudo em100 -s -p LOW -d u-boot.rom -c W25Q64DW -r
660
661A suitable clip for connecting over the SPI flash chip is here:
662
663 http://www.dediprog.com/pd/programmer-accessories/EM-TC-8
664
665This allows you to override the SPI flash contents for development purposes.
666Typically you can write to the em100 in around 1200ms, considerably faster
667than programming the real flash device each time. The only important
668limitation of the em100 is that it only supports SPI bus speeds up to 20MHz.
669This means that images must be set to boot with that speed. This is an
670Intel-specific feature - e.g. tools/ifttool has an option to set the SPI
671speed in the SPI descriptor region.
672
673If your chip/board uses an Intel Firmware Support Package (FSP) it is fairly
674easy to fit it in. You can follow the Minnowboard Max implementation, for
675example. Hopefully you will just need to create new files similar to those
676in arch/x86/cpu/baytrail which provide Bay Trail support.
677
678If you are not using an FSP you have more freedom and more responsibility.
679The ivybridge support works this way, although it still uses a ROM for
680graphics and still has binary blobs containing Intel code. You should aim to
681support all important peripherals on your platform including video and storage.
682Use the device tree for configuration where possible.
683
684For the microcode you can create a suitable device tree file using the
685microcode tool:
686
Simon Glass03e3c312015-08-15 14:37:48 -0600687 ./tools/microcode-tool -d microcode.dat -m <model> create
Simon Glass00bdd952015-01-27 22:13:46 -0700688
689or if you only have header files and not the full Intel microcode.dat database:
690
691 ./tools/microcode-tool -H BAY_TRAIL_FSP_KIT/Microcode/M0130673322.h \
692 -H BAY_TRAIL_FSP_KIT/Microcode/M0130679901.h \
Simon Glass03e3c312015-08-15 14:37:48 -0600693 -m all create
Simon Glass00bdd952015-01-27 22:13:46 -0700694
695These are written to arch/x86/dts/microcode/ by default.
696
697Note that it is possible to just add the micrcode for your CPU if you know its
698model. U-Boot prints this information when it starts
699
700 CPU: x86_64, vendor Intel, device 30673h
701
702so here we can use the M0130673322 file.
703
704If you platform can display POST codes on two little 7-segment displays on
705the board, then you can use post_code() calls from C or assembler to monitor
706boot progress. This can be good for debugging.
707
708If not, you can try to get serial working as early as possible. The early
709debug serial port may be useful here. See setup_early_uart() for an example.
710
Bin Meng12c75102015-08-02 20:33:35 -0700711During the U-Boot porting, one of the important steps is to write correct PIRQ
712routing information in the board device tree. Without it, device drivers in the
713Linux kernel won't function correctly due to interrupt is not working. Please
714refer to U-Boot doc [14] for the device tree bindings of Intel interrupt router.
715Here we have more details on the intel,pirq-routing property below.
716
717 intel,pirq-routing = <
718 PCI_BDF(0, 2, 0) INTA PIRQA
719 ...
720 >;
721
722As you see each entry has 3 cells. For the first one, we need describe all pci
723devices mounted on the board. For SoC devices, normally there is a chapter on
724the chipset datasheet which lists all the available PCI devices. For example on
725Bay Trail, this is chapter 4.3 (PCI configuration space). For the second one, we
726can get the interrupt pin either from datasheet or hardware via U-Boot shell.
727The reliable source is the hardware as sometimes chipset datasheet is not 100%
728up-to-date. Type 'pci header' plus the device's pci bus/device/function number
729from U-Boot shell below.
730
731 => pci header 0.1e.1
732 vendor ID = 0x8086
733 device ID = 0x0f08
734 ...
735 interrupt line = 0x09
736 interrupt pin = 0x04
737 ...
738
739It shows this PCI device is using INTD pin as it reports 4 in the interrupt pin
740register. Repeat this until you get interrupt pins for all the devices. The last
741cell is the PIRQ line which a particular interrupt pin is mapped to. On Intel
742chipset, the power-up default mapping is INTA/B/C/D maps to PIRQA/B/C/D. This
743can be changed by registers in LPC bridge. So far Intel FSP does not touch those
744registers so we can write down the PIRQ according to the default mapping rule.
745
746Once we get the PIRQ routing information in the device tree, the interrupt
747allocation and assignment will be done by U-Boot automatically. Now you can
748enable CONFIG_GENERATE_PIRQ_TABLE for testing Linux kernel using i8259 PIC and
749CONFIG_GENERATE_MP_TABLE for testing Linux kernel using local APIC and I/O APIC.
750
Simon Glass590870e2015-08-13 10:36:17 -0600751This script might be useful. If you feed it the output of 'pci long' from
752U-Boot then it will generate a device tree fragment with the interrupt
753configuration for each device (note it needs gawk 4.0.0):
754
755 $ cat console_output |awk '/PCI/ {device=$4} /interrupt line/ {line=$4} \
756 /interrupt pin/ {pin = $4; if (pin != "0x00" && pin != "0xff") \
757 {patsplit(device, bdf, "[0-9a-f]+"); \
758 printf "PCI_BDF(%d, %d, %d) INT%c PIRQ%c\n", strtonum("0x" bdf[1]), \
759 strtonum("0x" bdf[2]), bdf[3], strtonum(pin) + 64, 64 + strtonum(pin)}}'
760
761Example output:
762 PCI_BDF(0, 2, 0) INTA PIRQA
763 PCI_BDF(0, 3, 0) INTA PIRQA
764...
765
Bin Meng448719c2015-09-09 23:20:29 -0700766Porting Hints
767-------------
768
769Quark-specific considerations:
770
771To port U-Boot to other boards based on the Intel Quark SoC, a few things need
772to be taken care of. The first important part is the Memory Reference Code (MRC)
773parameters. Quark MRC supports memory-down configuration only. All these MRC
774parameters are supplied via the board device tree. To get started, first copy
775the MRC section of arch/x86/dts/galileo.dts to your board's device tree, then
776change these values by consulting board manuals or your hardware vendor.
777Available MRC parameter values are listed in include/dt-bindings/mrc/quark.h.
778The other tricky part is with PCIe. Quark SoC integrates two PCIe root ports,
779but by default they are held in reset after power on. In U-Boot, PCIe
780initialization is properly handled as per Quark's firmware writer guide.
781In your board support codes, you need provide two routines to aid PCIe
782initialization, which are board_assert_perst() and board_deassert_perst().
783The two routines need implement a board-specific mechanism to assert/deassert
784PCIe PERST# pin. Care must be taken that in those routines that any APIs that
785may trigger PCI enumeration process are strictly forbidden, as any access to
786PCIe root port's configuration registers will cause system hang while it is
787held in reset. For more details, check how they are implemented by the Intel
788Galileo board support codes in board/intel/galileo/galileo.c.
789
Bin Meng5dad97e2014-12-17 15:50:48 +0800790TODO List
791---------
Bin Meng5dad97e2014-12-17 15:50:48 +0800792- Audio
793- Chrome OS verified boot
794- SMI and ACPI support, to provide platform info and facilities to Linux
795
796References
797----------
798[1] http://www.coreboot.org
Bin Meng1ae5b782015-05-07 21:34:12 +0800799[2] http://www.qemu.org
800[3] http://www.coreboot.org/~stepan/pci8086,0166.rom
801[4] http://www.intel.com/content/www/us/en/embedded/design-tools/evaluation-platforms/atom-e660-eg20t-development-kit.html
802[5] http://www.intel.com/fsp
Bin Meng7aaff9b2015-07-06 16:31:35 +0800803[6] http://www.intel.com/content/www/us/en/secure/intelligent-systems/privileged/e6xx-35-b1-cmc22211.html
804[7] http://www.ami.com/products/bios-uefi-tools-and-utilities/bios-uefi-utilities/
805[8] http://en.wikipedia.org/wiki/Microcode
806[9] http://simplefirmware.org
807[10] http://www.intel.com/design/archives/processors/pro/docs/242016.htm
Simon Glass7bea5272015-07-27 15:47:31 -0600808[11] https://en.wikipedia.org/wiki/GUID_Partition_Table
809[12] http://events.linuxfoundation.org/sites/events/files/slides/chromeos_and_diy_vboot_0.pdf
810[13] http://events.linuxfoundation.org/sites/events/files/slides/elce-2014.pdf
Bin Meng12c75102015-08-02 20:33:35 -0700811[14] doc/device-tree-bindings/misc/intel,irq-router.txt