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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
21U-Boot also supports booting directly from x86 reset vector without coreboot,
Bin Meng1ae5b782015-05-07 21:34:12 +080022aka raw support or bare support. Currently Link, QEMU x86 targets and all
23Intel boards support running U-Boot 'bare metal'.
Bin Meng5dad97e2014-12-17 15:50:48 +080024
Simon Glass3a1a18f2015-01-27 22:13:47 -070025As for loading an OS, U-Boot supports directly booting a 32-bit or 64-bit
26Linux kernel as part of a FIT image. It also supports a compressed zImage.
Bin Meng5dad97e2014-12-17 15:50:48 +080027
28Build Instructions
29------------------
30Building U-Boot as a coreboot payload is just like building U-Boot for targets
31on other architectures, like below:
32
33$ make coreboot-x86_defconfig
34$ make all
35
Bin Meng1ae5b782015-05-07 21:34:12 +080036Note this default configuration will build a U-Boot payload for the QEMU board.
Bin Meng617b8672015-01-06 22:14:24 +080037To build a coreboot payload against another board, you can change the build
38configuration during the 'make menuconfig' process.
39
40x86 architecture --->
41 ...
Bin Meng1ae5b782015-05-07 21:34:12 +080042 (qemu-x86) Board configuration file
Bin Meng683b09d2015-06-03 09:20:04 +080043 (qemu-x86_i440fx) Board Device Tree Source (dts) file
Bin Meng1ae5b782015-05-07 21:34:12 +080044 (0x01920000) Board specific Cache-As-RAM (CAR) address
Bin Meng617b8672015-01-06 22:14:24 +080045 (0x4000) Board specific Cache-As-RAM (CAR) size
46
47Change the 'Board configuration file' and 'Board Device Tree Source (dts) file'
48to point to a new board. You can also change the Cache-As-RAM (CAR) related
49settings here if the default values do not fit your new board.
50
Simon Glass3a1a18f2015-01-27 22:13:47 -070051Building a ROM version of U-Boot (hereafter referred to as u-boot.rom) is a
Bin Meng5dad97e2014-12-17 15:50:48 +080052little bit tricky, as generally it requires several binary blobs which are not
53shipped in the U-Boot source tree. Due to this reason, the u-boot.rom build is
54not turned on by default in the U-Boot source tree. Firstly, you need turn it
Simon Glasseea0f112015-01-27 22:13:32 -070055on by enabling the ROM build:
Bin Meng5dad97e2014-12-17 15:50:48 +080056
Simon Glasseea0f112015-01-27 22:13:32 -070057$ export BUILD_ROM=y
58
59This tells the Makefile to build u-boot.rom as a target.
Bin Meng5dad97e2014-12-17 15:50:48 +080060
61Link-specific instructions:
62
63First, you need the following binary blobs:
64
65* descriptor.bin - Intel flash descriptor
66* me.bin - Intel Management Engine
67* mrc.bin - Memory Reference Code, which sets up SDRAM
68* video ROM - sets up the display
69
70You can get these binary blobs by:
71
72$ git clone http://review.coreboot.org/p/blobs.git
73$ cd blobs
74
75Find the following files:
76
77* ./mainboard/google/link/descriptor.bin
78* ./mainboard/google/link/me.bin
Simon Glass8712af92015-04-19 22:05:37 -060079* ./northbridge/intel/sandybridge/systemagent-r6.bin
Bin Meng5dad97e2014-12-17 15:50:48 +080080
81The 3rd one should be renamed to mrc.bin.
Bin Meng786a08e2015-07-06 16:31:33 +080082As for the video ROM, you can get it here [3] and rename it to vga.bin.
Bin Meng5dad97e2014-12-17 15:50:48 +080083Make sure all these binary blobs are put in the board directory.
84
85Now you can build U-Boot and obtain u-boot.rom:
86
87$ make chromebook_link_defconfig
88$ make all
89
90Intel Crown Bay specific instructions:
91
Bin Meng1ae5b782015-05-07 21:34:12 +080092U-Boot support of Intel Crown Bay board [4] relies on a binary blob called
93Firmware Support Package [5] to perform all the necessary initialization steps
Bin Meng5dad97e2014-12-17 15:50:48 +080094as documented in the BIOS Writer Guide, including initialization of the CPU,
95memory controller, chipset and certain bus interfaces.
96
97Download the Intel FSP for Atom E6xx series and Platform Controller Hub EG20T,
98install it on your host and locate the FSP binary blob. Note this platform
99also requires a Chipset Micro Code (CMC) state machine binary to be present in
100the SPI flash where u-boot.rom resides, and this CMC binary blob can be found
101in this FSP package too.
102
103* ./FSP/QUEENSBAY_FSP_GOLD_001_20-DECEMBER-2013.fd
104* ./Microcode/C0_22211.BIN
105
106Rename the first one to fsp.bin and second one to cmc.bin and put them in the
107board directory.
108
Bin Meng83d97122015-03-05 11:21:03 +0800109Note the FSP release version 001 has a bug which could cause random endless
110loop during the FspInit call. This bug was published by Intel although Intel
111did not describe any details. We need manually apply the patch to the FSP
112binary using any hex editor (eg: bvi). Go to the offset 0x1fcd8 of the FSP
113binary, change the following five bytes values from orginally E8 42 FF FF FF
114to B8 00 80 0B 00.
115
Bin Meng7aaff9b2015-07-06 16:31:35 +0800116As for the video ROM, you need manually extract it from the Intel provided
117BIOS for Crown Bay here [6], using the AMI MMTool [7]. Check PCI option ROM
118ID 8086:4108, extract and save it as vga.bin in the board directory.
119
Bin Meng617b8672015-01-06 22:14:24 +0800120Now you can build U-Boot and obtain u-boot.rom
Bin Meng5dad97e2014-12-17 15:50:48 +0800121
122$ make crownbay_defconfig
123$ make all
124
Simon Glass3a1a18f2015-01-27 22:13:47 -0700125Intel Minnowboard Max instructions:
126
127This uses as FSP as with Crown Bay, except it is for the Atom E3800 series.
128Download this and get the .fd file (BAYTRAIL_FSP_GOLD_003_16-SEP-2014.fd at
129the time of writing). Put it in the board directory:
130board/intel/minnowmax/fsp.bin
131
132Obtain the VGA RAM (Vga.dat at the time of writing) and put it into the same
133directory: board/intel/minnowmax/vga.bin
134
Simon Glass68522482015-04-25 11:46:43 -0600135You still need two more binary blobs. The first comes from the original
136firmware image available from:
137
138http://firmware.intel.com/sites/default/files/2014-WW42.4-MinnowBoardMax.73-64-bit.bin_Release.zip
139
140Unzip it:
141
142 $ unzip 2014-WW42.4-MinnowBoardMax.73-64-bit.bin_Release.zip
Simon Glass3a1a18f2015-01-27 22:13:47 -0700143
144Use ifdtool in the U-Boot tools directory to extract the images from that
145file, for example:
146
Simon Glass68522482015-04-25 11:46:43 -0600147 $ ./tools/ifdtool -x MNW2MAX1.X64.0073.R02.1409160934.bin
148
149This will provide the descriptor file - copy this into the correct place:
150
151 $ cp flashregion_0_flashdescriptor.bin board/intel/minnowmax/descriptor.bin
152
153Then do the same with the sample SPI image provided in the FSP (SPI.bin at
154the time of writing) to obtain the last image. Note that this will also
155produce a flash descriptor file, but it does not seem to work, probably
156because it is not designed for the Minnowmax. That is why you need to get
157the flash descriptor from the original firmware as above.
158
Simon Glass3a1a18f2015-01-27 22:13:47 -0700159 $ ./tools/ifdtool -x BayleyBay/SPI.bin
160 $ cp flashregion_2_intel_me.bin board/intel/minnowmax/me.bin
Simon Glass3a1a18f2015-01-27 22:13:47 -0700161
162Now you can build U-Boot and obtain u-boot.rom
163
164$ make minnowmax_defconfig
165$ make all
166
Simon Glassdf898672015-07-03 18:28:28 -0600167Checksums are as follows (but note that newer versions will invalidate this):
168
169$ md5sum -b board/intel/minnowmax/*.bin
170ffda9a3b94df5b74323afb328d51e6b4 board/intel/minnowmax/descriptor.bin
17169f65b9a580246291d20d08cbef9d7c5 board/intel/minnowmax/fsp.bin
172894a97d371544ec21de9c3e8e1716c4b board/intel/minnowmax/me.bin
173a2588537da387da592a27219d56e9962 board/intel/minnowmax/vga.bin
174
Simon Glass537ccba2015-07-03 18:28:24 -0600175The ROM image is broken up into these parts:
176
177Offset Description Controlling config
178------------------------------------------------------------
179000000 descriptor.bin Hard-coded to 0 in ifdtool
180001000 me.bin Set by the descriptor
181500000 <spare>
182700000 u-boot-dtb.bin CONFIG_SYS_TEXT_BASE
183790000 vga.bin CONFIG_X86_OPTION_ROM_ADDR
1847c0000 fsp.bin CONFIG_FSP_ADDR
1857f8000 <spare> (depends on size of fsp.bin)
1867fe000 Environment CONFIG_ENV_OFFSET
1877ff800 U-Boot 16-bit boot CONFIG_SYS_X86_START16
188
189Overall ROM image size is controlled by CONFIG_ROM_SIZE.
190
191
Bin Meng67582c02015-02-04 16:26:14 +0800192Intel Galileo instructions:
193
194Only one binary blob is needed for Remote Management Unit (RMU) within Intel
195Quark SoC. Not like FSP, U-Boot does not call into the binary. The binary is
196needed by the Quark SoC itself.
197
198You can get the binary blob from Quark Board Support Package from Intel website:
199
200* ./QuarkSocPkg/QuarkNorthCluster/Binary/QuarkMicrocode/RMU.bin
201
202Rename the file and put it to the board directory by:
203
204 $ cp RMU.bin board/intel/galileo/rmu.bin
205
206Now you can build U-Boot and obtain u-boot.rom
207
208$ make galileo_defconfig
209$ make all
Simon Glass3a1a18f2015-01-27 22:13:47 -0700210
Bin Meng1ae5b782015-05-07 21:34:12 +0800211QEMU x86 target instructions:
212
213To build u-boot.rom for QEMU x86 targets, just simply run
214
215$ make qemu-x86_defconfig
216$ make all
217
Bin Meng683b09d2015-06-03 09:20:04 +0800218Note this default configuration will build a U-Boot for the QEMU x86 i440FX
219board. To build a U-Boot against QEMU x86 Q35 board, you can change the build
220configuration during the 'make menuconfig' process like below:
221
222Device Tree Control --->
223 ...
224 (qemu-x86_q35) Default Device Tree for DT control
225
Bin Meng617b8672015-01-06 22:14:24 +0800226Test with coreboot
227------------------
228For testing U-Boot as the coreboot payload, there are things that need be paid
229attention to. coreboot supports loading an ELF executable and a 32-bit plain
230binary, as well as other supported payloads. With the default configuration,
231U-Boot is set up to use a separate Device Tree Blob (dtb). As of today, the
232generated u-boot-dtb.bin needs to be packaged by the cbfstool utility (a tool
233provided by coreboot) manually as coreboot's 'make menuconfig' does not provide
234this capability yet. The command is as follows:
235
236# in the coreboot root directory
237$ ./build/util/cbfstool/cbfstool build/coreboot.rom add-flat-binary \
238 -f u-boot-dtb.bin -n fallback/payload -c lzma -l 0x1110000 -e 0x1110015
239
240Make sure 0x1110000 matches CONFIG_SYS_TEXT_BASE and 0x1110015 matches the
241symbol address of _start (in arch/x86/cpu/start.S).
242
243If you want to use ELF as the coreboot payload, change U-Boot configuration to
Simon Glasseea0f112015-01-27 22:13:32 -0700244use CONFIG_OF_EMBED instead of CONFIG_OF_SEPARATE.
Bin Meng617b8672015-01-06 22:14:24 +0800245
Simon Glass3a1a18f2015-01-27 22:13:47 -0700246To enable video you must enable these options in coreboot:
247
248 - Set framebuffer graphics resolution (1280x1024 32k-color (1:5:5))
249 - Keep VESA framebuffer
250
251At present it seems that for Minnowboard Max, coreboot does not pass through
252the video information correctly (it always says the resolution is 0x0). This
253works correctly for link though.
254
Bin Meng1ae5b782015-05-07 21:34:12 +0800255Test with QEMU
256--------------
257QEMU is a fancy emulator that can enable us to test U-Boot without access to
Bin Meng9c4f5412015-05-11 07:36:30 +0800258a real x86 board. Please make sure your QEMU version is 2.3.0 or above test
259U-Boot. To launch QEMU with u-boot.rom, call QEMU as follows:
Bin Meng1ae5b782015-05-07 21:34:12 +0800260
261$ qemu-system-i386 -nographic -bios path/to/u-boot.rom
262
263This will instantiate an emulated x86 board with i440FX and PIIX chipset. QEMU
264also supports emulating an x86 board with Q35 and ICH9 based chipset, which is
265also supported by U-Boot. To instantiate such a machine, call QEMU with:
266
267$ qemu-system-i386 -nographic -bios path/to/u-boot.rom -M q35
268
269Note by default QEMU instantiated boards only have 128 MiB system memory. But
270it is enough to have U-Boot boot and function correctly. You can increase the
271system memory by pass '-m' parameter to QEMU if you want more memory:
272
273$ qemu-system-i386 -nographic -bios path/to/u-boot.rom -m 1024
274
275This creates a board with 1 GiB system memory. Currently U-Boot for QEMU only
276supports 3 GiB maximum system memory and reserves the last 1 GiB address space
277for PCI device memory-mapped I/O and other stuff, so the maximum value of '-m'
278would be 3072.
Simon Glass3a1a18f2015-01-27 22:13:47 -0700279
Bin Meng9c4f5412015-05-11 07:36:30 +0800280QEMU emulates a graphic card which U-Boot supports. Removing '-nographic' will
281show QEMU's VGA console window. Note this will disable QEMU's serial output.
282If you want to check both consoles, use '-serial stdio'.
283
Bin Menga2eb65f2015-07-27 19:16:08 +0800284Multicore is also supported by QEMU via '-smp n' where n is the number of cores
285to instantiate. Currently the default U-Boot built for QEMU supports 2 cores.
286In order to support more cores, you need add additional cpu nodes in the device
287tree and change CONFIG_MAX_CPUS accordingly.
288
Bin Meng5dad97e2014-12-17 15:50:48 +0800289CPU Microcode
290-------------
Bin Meng7aaff9b2015-07-06 16:31:35 +0800291Modern CPUs usually require a special bit stream called microcode [8] to be
Bin Meng5dad97e2014-12-17 15:50:48 +0800292loaded on the processor after power up in order to function properly. U-Boot
293has already integrated these as hex dumps in the source tree.
294
Bin Meng1281a1f2015-06-23 12:18:53 +0800295SMP Support
296-----------
297On a multicore system, U-Boot is executed on the bootstrap processor (BSP).
298Additional application processors (AP) can be brought up by U-Boot. In order to
299have an SMP kernel to discover all of the available processors, U-Boot needs to
300prepare configuration tables which contain the multi-CPUs information before
301loading the OS kernel. Currently U-Boot supports generating two types of tables
Bin Meng7aaff9b2015-07-06 16:31:35 +0800302for SMP, called Simple Firmware Interface (SFI) [9] and Multi-Processor (MP)
303[10] tables. The writing of these two tables are controlled by two Kconfig
304options GENERATE_SFI_TABLE and GENERATE_MP_TABLE.
Bin Meng1281a1f2015-06-23 12:18:53 +0800305
Bin Meng5dad97e2014-12-17 15:50:48 +0800306Driver Model
307------------
308x86 has been converted to use driver model for serial and GPIO.
309
310Device Tree
311-----------
312x86 uses device tree to configure the board thus requires CONFIG_OF_CONTROL to
Bin Meng617b8672015-01-06 22:14:24 +0800313be turned on. Not every device on the board is configured via device tree, but
Bin Meng5dad97e2014-12-17 15:50:48 +0800314more and more devices will be added as time goes by. Check out the directory
315arch/x86/dts/ for these device tree source files.
316
Simon Glasscb3b2e62015-01-01 16:18:15 -0700317Useful Commands
318---------------
Simon Glasscb3b2e62015-01-01 16:18:15 -0700319In keeping with the U-Boot philosophy of providing functions to check and
320adjust internal settings, there are several x86-specific commands that may be
321useful:
322
323hob - Display information about Firmware Support Package (FSP) Hand-off
324 Block. This is only available on platforms which use FSP, mostly
325 Atom.
326iod - Display I/O memory
327iow - Write I/O memory
328mtrr - List and set the Memory Type Range Registers (MTRR). These are used to
329 tell the CPU whether memory is cacheable and if so the cache write
330 mode to use. U-Boot sets up some reasonable values but you can
331 adjust then with this command.
332
Simon Glass7bea5272015-07-27 15:47:31 -0600333Booting Ubuntu
334--------------
335As an example of how to set up your boot flow with U-Boot, here are
336instructions for starting Ubuntu from U-Boot. These instructions have been
337tested on Minnowboard MAX with a SATA driver but are equally applicable on
338other platforms and other media. There are really only four steps and its a
339very simple script, but a more detailed explanation is provided here for
340completeness.
341
342Note: It is possible to set up U-Boot to boot automatically using syslinux.
343It could also use the grub.cfg file (/efi/ubuntu/grub.cfg) to obtain the
344GUID. If you figure these out, please post patches to this README.
345
346Firstly, you will need Ubunutu installed on an available disk. It should be
347possible to make U-Boot start a USB start-up disk but for now let's assume
348that you used another boot loader to install Ubuntu.
349
350Use the U-Boot command line to find the UUID of the partition you want to
351boot. For example our disk is SCSI device 0:
352
353=> part list scsi 0
354
355Partition Map for SCSI device 0 -- Partition Type: EFI
356
357 Part Start LBA End LBA Name
358 Attributes
359 Type GUID
360 Partition GUID
361 1 0x00000800 0x001007ff ""
362 attrs: 0x0000000000000000
363 type: c12a7328-f81f-11d2-ba4b-00a0c93ec93b
364 guid: 9d02e8e4-4d59-408f-a9b0-fd497bc9291c
365 2 0x00100800 0x037d8fff ""
366 attrs: 0x0000000000000000
367 type: 0fc63daf-8483-4772-8e79-3d69d8477de4
368 guid: 965c59ee-1822-4326-90d2-b02446050059
369 3 0x037d9000 0x03ba27ff ""
370 attrs: 0x0000000000000000
371 type: 0657fd6d-a4ab-43c4-84e5-0933c84b4f4f
372 guid: 2c4282bd-1e82-4bcf-a5ff-51dedbf39f17
373 =>
374
375This shows that your SCSI disk has three partitions. The really long hex
376strings are called Globally Unique Identifiers (GUIDs). You can look up the
377'type' ones here [11]. On this disk the first partition is for EFI and is in
378VFAT format (DOS/Windows):
379
380 => fatls scsi 0:1
381 efi/
382
383 0 file(s), 1 dir(s)
384
385
386Partition 2 is 'Linux filesystem data' so that will be our root disk. It is
387in ext2 format:
388
389 => ext2ls scsi 0:2
390 <DIR> 4096 .
391 <DIR> 4096 ..
392 <DIR> 16384 lost+found
393 <DIR> 4096 boot
394 <DIR> 12288 etc
395 <DIR> 4096 media
396 <DIR> 4096 bin
397 <DIR> 4096 dev
398 <DIR> 4096 home
399 <DIR> 4096 lib
400 <DIR> 4096 lib64
401 <DIR> 4096 mnt
402 <DIR> 4096 opt
403 <DIR> 4096 proc
404 <DIR> 4096 root
405 <DIR> 4096 run
406 <DIR> 12288 sbin
407 <DIR> 4096 srv
408 <DIR> 4096 sys
409 <DIR> 4096 tmp
410 <DIR> 4096 usr
411 <DIR> 4096 var
412 <SYM> 33 initrd.img
413 <SYM> 30 vmlinuz
414 <DIR> 4096 cdrom
415 <SYM> 33 initrd.img.old
416 =>
417
418and if you look in the /boot directory you will see the kernel:
419
420 => ext2ls scsi 0:2 /boot
421 <DIR> 4096 .
422 <DIR> 4096 ..
423 <DIR> 4096 efi
424 <DIR> 4096 grub
425 3381262 System.map-3.13.0-32-generic
426 1162712 abi-3.13.0-32-generic
427 165611 config-3.13.0-32-generic
428 176500 memtest86+.bin
429 178176 memtest86+.elf
430 178680 memtest86+_multiboot.bin
431 5798112 vmlinuz-3.13.0-32-generic
432 165762 config-3.13.0-58-generic
433 1165129 abi-3.13.0-58-generic
434 5823136 vmlinuz-3.13.0-58-generic
435 19215259 initrd.img-3.13.0-58-generic
436 3391763 System.map-3.13.0-58-generic
437 5825048 vmlinuz-3.13.0-58-generic.efi.signed
438 28304443 initrd.img-3.13.0-32-generic
439 =>
440
441The 'vmlinuz' files contain a packaged Linux kernel. The format is a kind of
442self-extracting compressed file mixed with some 'setup' configuration data.
443Despite its size (uncompressed it is >10MB) this only includes a basic set of
444device drivers, enough to boot on most hardware types.
445
446The 'initrd' files contain a RAM disk. This is something that can be loaded
447into RAM and will appear to Linux like a disk. Ubuntu uses this to hold lots
448of drivers for whatever hardware you might have. It is loaded before the
449real root disk is accessed.
450
451The numbers after the end of each file are the version. Here it is Linux
452version 3.13. You can find the source code for this in the Linux tree with
453the tag v3.13. The '.0' allows for additional Linux releases to fix problems,
454but normally this is not needed. The '-58' is used by Ubuntu. Each time they
455release a new kernel they increment this number. New Ubuntu versions might
456include kernel patches to fix reported bugs. Stable kernels can exist for
457some years so this number can get quite high.
458
459The '.efi.signed' kernel is signed for EFI's secure boot. U-Boot has its own
460secure boot mechanism - see [12] [13] and cannot read .efi files at present.
461
462To boot Ubuntu from U-Boot the steps are as follows:
463
4641. Set up the boot arguments. Use the GUID for the partition you want to
465boot:
466
467 => setenv bootargs root=/dev/disk/by-partuuid/965c59ee-1822-4326-90d2-b02446050059 ro
468
469Here root= tells Linux the location of its root disk. The disk is specified
470by its GUID, using '/dev/disk/by-partuuid/', a Linux path to a 'directory'
471containing all the GUIDs Linux has found. When it starts up, there will be a
472file in that directory with this name in it. It is also possible to use a
473device name here, see later.
474
4752. Load the kernel. Since it is an ext2/4 filesystem we can do:
476
477 => ext2load scsi 0:2 03000000 /boot/vmlinuz-3.13.0-58-generic
478
479The address 30000000 is arbitrary, but there seem to be problems with using
480small addresses (sometimes Linux cannot find the ramdisk). This is 48MB into
481the start of RAM (which is at 0 on x86).
482
4833. Load the ramdisk (to 64MB):
484
485 => ext2load scsi 0:2 04000000 /boot/initrd.img-3.13.0-58-generic
486
4874. Start up the kernel. We need to know the size of the ramdisk, but can use
488a variable for that. U-Boot sets 'filesize' to the size of the last file it
489loaded.
490
491 => zboot 03000000 0 04000000 ${filesize}
492
493Type 'help zboot' if you want to see what the arguments are. U-Boot on x86 is
494quite verbose when it boots a kernel. You should see these messages from
495U-Boot:
496
497 Valid Boot Flag
498 Setup Size = 0x00004400
499 Magic signature found
500 Using boot protocol version 2.0c
501 Linux kernel version 3.13.0-58-generic (buildd@allspice) #97-Ubuntu SMP Wed Jul 8 02:56:15 UTC 2015
502 Building boot_params at 0x00090000
503 Loading bzImage at address 100000 (5805728 bytes)
504 Magic signature found
505 Initial RAM disk at linear address 0x04000000, size 19215259 bytes
506 Kernel command line: "console=ttyS0,115200 root=/dev/disk/by-partuuid/965c59ee-1822-4326-90d2-b02446050059 ro"
507
508 Starting kernel ...
509
510U-Boot prints out some bootstage timing. This is more useful if you put the
511above commands into a script since then it will be faster.
512
513 Timer summary in microseconds:
514 Mark Elapsed Stage
515 0 0 reset
516 241,535 241,535 board_init_r
517 2,421,611 2,180,076 id=64
518 2,421,790 179 id=65
519 2,428,215 6,425 main_loop
520 48,860,584 46,432,369 start_kernel
521
522 Accumulated time:
523 240,329 ahci
524 1,422,704 vesa display
525
526Now the kernel actually starts:
527
528 [ 0.000000] Initializing cgroup subsys cpuset
529 [ 0.000000] Initializing cgroup subsys cpu
530 [ 0.000000] Initializing cgroup subsys cpuacct
531 [ 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)
532 [ 0.000000] Command line: console=ttyS0,115200 root=/dev/disk/by-partuuid/965c59ee-1822-4326-90d2-b02446050059 ro
533
534It continues for a long time. Along the way you will see it pick up your
535ramdisk:
536
537 [ 0.000000] RAMDISK: [mem 0x04000000-0x05253fff]
538...
539 [ 0.788540] Trying to unpack rootfs image as initramfs...
540 [ 1.540111] Freeing initrd memory: 18768K (ffff880004000000 - ffff880005254000)
541...
542
543Later it actually starts using it:
544
545 Begin: Running /scripts/local-premount ... done.
546
547You should also see your boot disk turn up:
548
549 [ 4.357243] scsi 1:0:0:0: Direct-Access ATA ADATA SP310 5.2 PQ: 0 ANSI: 5
550 [ 4.366860] sd 1:0:0:0: [sda] 62533296 512-byte logical blocks: (32.0 GB/29.8 GiB)
551 [ 4.375677] sd 1:0:0:0: Attached scsi generic sg0 type 0
552 [ 4.381859] sd 1:0:0:0: [sda] Write Protect is off
553 [ 4.387452] sd 1:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
554 [ 4.399535] sda: sda1 sda2 sda3
555
556Linux has found the three partitions (sda1-3). Mercifully it doesn't print out
557the GUIDs. In step 1 above we could have used:
558
559 setenv bootargs root=/dev/sda2 ro
560
561instead of the GUID. However if you add another drive to your board the
562numbering may change whereas the GUIDs will not. So if your boot partition
563becomes sdb2, it will still boot. For embedded systems where you just want to
564boot the first disk, you have that option.
565
566The last thing you will see on the console is mention of plymouth (which
567displays the Ubuntu start-up screen) and a lot of 'Starting' messages:
568
569 * Starting Mount filesystems on boot [ OK ]
570
571After a pause you should see a login screen on your display and you are done.
572
573If you want to put this in a script you can use something like this:
574
575 setenv bootargs root=UUID=b2aaf743-0418-4d90-94cc-3e6108d7d968 ro
576 setenv boot zboot 03000000 0 04000000 \${filesize}
577 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"
578 saveenv
579
580The \ is to tell the shell not to evaluate ${filesize} as part of the setenv
581command.
582
583You will also need to add this to your board configuration file, e.g.
584include/configs/minnowmax.h:
585
586 #define CONFIG_BOOTDELAY 2
587
588Now when you reset your board it wait a few seconds (in case you want to
589interrupt) and then should boot straight into Ubuntu.
590
591You can also bake this behaviour into your build by hard-coding the
592environment variables if you add this to minnowmax.h:
593
594#undef CONFIG_BOOTARGS
595#undef CONFIG_BOOTCOMMAND
596
597#define CONFIG_BOOTARGS \
598 "root=/dev/sda2 ro"
599#define CONFIG_BOOTCOMMAND \
600 "ext2load scsi 0:2 03000000 /boot/vmlinuz-3.13.0-58-generic; " \
601 "ext2load scsi 0:2 04000000 /boot/initrd.img-3.13.0-58-generic; " \
602 "run boot"
603
604#undef CONFIG_EXTRA_ENV_SETTINGS
605#define CONFIG_EXTRA_ENV_SETTINGS "boot=zboot 03000000 0 04000000 ${filesize}"
606
607
Simon Glass00bdd952015-01-27 22:13:46 -0700608Development Flow
609----------------
Simon Glass00bdd952015-01-27 22:13:46 -0700610These notes are for those who want to port U-Boot to a new x86 platform.
611
612Since x86 CPUs boot from SPI flash, a SPI flash emulator is a good investment.
613The Dediprog em100 can be used on Linux. The em100 tool is available here:
614
615 http://review.coreboot.org/p/em100.git
616
617On Minnowboard Max the following command line can be used:
618
619 sudo em100 -s -p LOW -d u-boot.rom -c W25Q64DW -r
620
621A suitable clip for connecting over the SPI flash chip is here:
622
623 http://www.dediprog.com/pd/programmer-accessories/EM-TC-8
624
625This allows you to override the SPI flash contents for development purposes.
626Typically you can write to the em100 in around 1200ms, considerably faster
627than programming the real flash device each time. The only important
628limitation of the em100 is that it only supports SPI bus speeds up to 20MHz.
629This means that images must be set to boot with that speed. This is an
630Intel-specific feature - e.g. tools/ifttool has an option to set the SPI
631speed in the SPI descriptor region.
632
633If your chip/board uses an Intel Firmware Support Package (FSP) it is fairly
634easy to fit it in. You can follow the Minnowboard Max implementation, for
635example. Hopefully you will just need to create new files similar to those
636in arch/x86/cpu/baytrail which provide Bay Trail support.
637
638If you are not using an FSP you have more freedom and more responsibility.
639The ivybridge support works this way, although it still uses a ROM for
640graphics and still has binary blobs containing Intel code. You should aim to
641support all important peripherals on your platform including video and storage.
642Use the device tree for configuration where possible.
643
644For the microcode you can create a suitable device tree file using the
645microcode tool:
646
647 ./tools/microcode-tool -d microcode.dat create <model>
648
649or if you only have header files and not the full Intel microcode.dat database:
650
651 ./tools/microcode-tool -H BAY_TRAIL_FSP_KIT/Microcode/M0130673322.h \
652 -H BAY_TRAIL_FSP_KIT/Microcode/M0130679901.h \
653 create all
654
655These are written to arch/x86/dts/microcode/ by default.
656
657Note that it is possible to just add the micrcode for your CPU if you know its
658model. U-Boot prints this information when it starts
659
660 CPU: x86_64, vendor Intel, device 30673h
661
662so here we can use the M0130673322 file.
663
664If you platform can display POST codes on two little 7-segment displays on
665the board, then you can use post_code() calls from C or assembler to monitor
666boot progress. This can be good for debugging.
667
668If not, you can try to get serial working as early as possible. The early
669debug serial port may be useful here. See setup_early_uart() for an example.
670
Bin Meng12c75102015-08-02 20:33:35 -0700671During the U-Boot porting, one of the important steps is to write correct PIRQ
672routing information in the board device tree. Without it, device drivers in the
673Linux kernel won't function correctly due to interrupt is not working. Please
674refer to U-Boot doc [14] for the device tree bindings of Intel interrupt router.
675Here we have more details on the intel,pirq-routing property below.
676
677 intel,pirq-routing = <
678 PCI_BDF(0, 2, 0) INTA PIRQA
679 ...
680 >;
681
682As you see each entry has 3 cells. For the first one, we need describe all pci
683devices mounted on the board. For SoC devices, normally there is a chapter on
684the chipset datasheet which lists all the available PCI devices. For example on
685Bay Trail, this is chapter 4.3 (PCI configuration space). For the second one, we
686can get the interrupt pin either from datasheet or hardware via U-Boot shell.
687The reliable source is the hardware as sometimes chipset datasheet is not 100%
688up-to-date. Type 'pci header' plus the device's pci bus/device/function number
689from U-Boot shell below.
690
691 => pci header 0.1e.1
692 vendor ID = 0x8086
693 device ID = 0x0f08
694 ...
695 interrupt line = 0x09
696 interrupt pin = 0x04
697 ...
698
699It shows this PCI device is using INTD pin as it reports 4 in the interrupt pin
700register. Repeat this until you get interrupt pins for all the devices. The last
701cell is the PIRQ line which a particular interrupt pin is mapped to. On Intel
702chipset, the power-up default mapping is INTA/B/C/D maps to PIRQA/B/C/D. This
703can be changed by registers in LPC bridge. So far Intel FSP does not touch those
704registers so we can write down the PIRQ according to the default mapping rule.
705
706Once we get the PIRQ routing information in the device tree, the interrupt
707allocation and assignment will be done by U-Boot automatically. Now you can
708enable CONFIG_GENERATE_PIRQ_TABLE for testing Linux kernel using i8259 PIC and
709CONFIG_GENERATE_MP_TABLE for testing Linux kernel using local APIC and I/O APIC.
710
Bin Meng5dad97e2014-12-17 15:50:48 +0800711TODO List
712---------
Bin Meng5dad97e2014-12-17 15:50:48 +0800713- Audio
714- Chrome OS verified boot
715- SMI and ACPI support, to provide platform info and facilities to Linux
716
717References
718----------
719[1] http://www.coreboot.org
Bin Meng1ae5b782015-05-07 21:34:12 +0800720[2] http://www.qemu.org
721[3] http://www.coreboot.org/~stepan/pci8086,0166.rom
722[4] http://www.intel.com/content/www/us/en/embedded/design-tools/evaluation-platforms/atom-e660-eg20t-development-kit.html
723[5] http://www.intel.com/fsp
Bin Meng7aaff9b2015-07-06 16:31:35 +0800724[6] http://www.intel.com/content/www/us/en/secure/intelligent-systems/privileged/e6xx-35-b1-cmc22211.html
725[7] http://www.ami.com/products/bios-uefi-tools-and-utilities/bios-uefi-utilities/
726[8] http://en.wikipedia.org/wiki/Microcode
727[9] http://simplefirmware.org
728[10] http://www.intel.com/design/archives/processors/pro/docs/242016.htm
Simon Glass7bea5272015-07-27 15:47:31 -0600729[11] https://en.wikipedia.org/wiki/GUID_Partition_Table
730[12] http://events.linuxfoundation.org/sites/events/files/slides/chromeos_and_diy_vboot_0.pdf
731[13] http://events.linuxfoundation.org/sites/events/files/slides/elce-2014.pdf
Bin Meng12c75102015-08-02 20:33:35 -0700732[14] doc/device-tree-bindings/misc/intel,irq-router.txt