blob: 1271e5edea3a427debce1ff202eecb6aa7cbc4f2 [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
298to instantiate. Currently the default U-Boot built for QEMU supports 2 cores.
299In order to support more cores, you need add additional cpu nodes in the device
300tree and change CONFIG_MAX_CPUS accordingly.
301
Bin Meng5dad97e2014-12-17 15:50:48 +0800302CPU Microcode
303-------------
Bin Meng7aaff9b2015-07-06 16:31:35 +0800304Modern CPUs usually require a special bit stream called microcode [8] to be
Bin Meng5dad97e2014-12-17 15:50:48 +0800305loaded on the processor after power up in order to function properly. U-Boot
306has already integrated these as hex dumps in the source tree.
307
Bin Meng1281a1f2015-06-23 12:18:53 +0800308SMP Support
309-----------
310On a multicore system, U-Boot is executed on the bootstrap processor (BSP).
311Additional application processors (AP) can be brought up by U-Boot. In order to
312have an SMP kernel to discover all of the available processors, U-Boot needs to
313prepare configuration tables which contain the multi-CPUs information before
314loading the OS kernel. Currently U-Boot supports generating two types of tables
Bin Meng7aaff9b2015-07-06 16:31:35 +0800315for SMP, called Simple Firmware Interface (SFI) [9] and Multi-Processor (MP)
316[10] tables. The writing of these two tables are controlled by two Kconfig
317options GENERATE_SFI_TABLE and GENERATE_MP_TABLE.
Bin Meng1281a1f2015-06-23 12:18:53 +0800318
Bin Meng5dad97e2014-12-17 15:50:48 +0800319Driver Model
320------------
321x86 has been converted to use driver model for serial and GPIO.
322
323Device Tree
324-----------
325x86 uses device tree to configure the board thus requires CONFIG_OF_CONTROL to
Bin Meng617b8672015-01-06 22:14:24 +0800326be turned on. Not every device on the board is configured via device tree, but
Bin Meng5dad97e2014-12-17 15:50:48 +0800327more and more devices will be added as time goes by. Check out the directory
328arch/x86/dts/ for these device tree source files.
329
Simon Glasscb3b2e62015-01-01 16:18:15 -0700330Useful Commands
331---------------
Simon Glasscb3b2e62015-01-01 16:18:15 -0700332In keeping with the U-Boot philosophy of providing functions to check and
333adjust internal settings, there are several x86-specific commands that may be
334useful:
335
Bin Meng62716eb2015-10-10 01:47:58 -0700336fsp - Display information about Intel Firmware Support Package (FSP).
337 This is only available on platforms which use FSP, mostly Atom.
Simon Glasscb3b2e62015-01-01 16:18:15 -0700338iod - Display I/O memory
339iow - Write I/O memory
340mtrr - List and set the Memory Type Range Registers (MTRR). These are used to
341 tell the CPU whether memory is cacheable and if so the cache write
342 mode to use. U-Boot sets up some reasonable values but you can
343 adjust then with this command.
344
Simon Glass7bea5272015-07-27 15:47:31 -0600345Booting Ubuntu
346--------------
347As an example of how to set up your boot flow with U-Boot, here are
348instructions for starting Ubuntu from U-Boot. These instructions have been
349tested on Minnowboard MAX with a SATA driver but are equally applicable on
350other platforms and other media. There are really only four steps and its a
351very simple script, but a more detailed explanation is provided here for
352completeness.
353
354Note: It is possible to set up U-Boot to boot automatically using syslinux.
355It could also use the grub.cfg file (/efi/ubuntu/grub.cfg) to obtain the
356GUID. If you figure these out, please post patches to this README.
357
358Firstly, you will need Ubunutu installed on an available disk. It should be
359possible to make U-Boot start a USB start-up disk but for now let's assume
360that you used another boot loader to install Ubuntu.
361
362Use the U-Boot command line to find the UUID of the partition you want to
363boot. For example our disk is SCSI device 0:
364
365=> part list scsi 0
366
367Partition Map for SCSI device 0 -- Partition Type: EFI
368
369 Part Start LBA End LBA Name
370 Attributes
371 Type GUID
372 Partition GUID
373 1 0x00000800 0x001007ff ""
374 attrs: 0x0000000000000000
375 type: c12a7328-f81f-11d2-ba4b-00a0c93ec93b
376 guid: 9d02e8e4-4d59-408f-a9b0-fd497bc9291c
377 2 0x00100800 0x037d8fff ""
378 attrs: 0x0000000000000000
379 type: 0fc63daf-8483-4772-8e79-3d69d8477de4
380 guid: 965c59ee-1822-4326-90d2-b02446050059
381 3 0x037d9000 0x03ba27ff ""
382 attrs: 0x0000000000000000
383 type: 0657fd6d-a4ab-43c4-84e5-0933c84b4f4f
384 guid: 2c4282bd-1e82-4bcf-a5ff-51dedbf39f17
385 =>
386
387This shows that your SCSI disk has three partitions. The really long hex
388strings are called Globally Unique Identifiers (GUIDs). You can look up the
389'type' ones here [11]. On this disk the first partition is for EFI and is in
390VFAT format (DOS/Windows):
391
392 => fatls scsi 0:1
393 efi/
394
395 0 file(s), 1 dir(s)
396
397
398Partition 2 is 'Linux filesystem data' so that will be our root disk. It is
399in ext2 format:
400
401 => ext2ls scsi 0:2
402 <DIR> 4096 .
403 <DIR> 4096 ..
404 <DIR> 16384 lost+found
405 <DIR> 4096 boot
406 <DIR> 12288 etc
407 <DIR> 4096 media
408 <DIR> 4096 bin
409 <DIR> 4096 dev
410 <DIR> 4096 home
411 <DIR> 4096 lib
412 <DIR> 4096 lib64
413 <DIR> 4096 mnt
414 <DIR> 4096 opt
415 <DIR> 4096 proc
416 <DIR> 4096 root
417 <DIR> 4096 run
418 <DIR> 12288 sbin
419 <DIR> 4096 srv
420 <DIR> 4096 sys
421 <DIR> 4096 tmp
422 <DIR> 4096 usr
423 <DIR> 4096 var
424 <SYM> 33 initrd.img
425 <SYM> 30 vmlinuz
426 <DIR> 4096 cdrom
427 <SYM> 33 initrd.img.old
428 =>
429
430and if you look in the /boot directory you will see the kernel:
431
432 => ext2ls scsi 0:2 /boot
433 <DIR> 4096 .
434 <DIR> 4096 ..
435 <DIR> 4096 efi
436 <DIR> 4096 grub
437 3381262 System.map-3.13.0-32-generic
438 1162712 abi-3.13.0-32-generic
439 165611 config-3.13.0-32-generic
440 176500 memtest86+.bin
441 178176 memtest86+.elf
442 178680 memtest86+_multiboot.bin
443 5798112 vmlinuz-3.13.0-32-generic
444 165762 config-3.13.0-58-generic
445 1165129 abi-3.13.0-58-generic
446 5823136 vmlinuz-3.13.0-58-generic
447 19215259 initrd.img-3.13.0-58-generic
448 3391763 System.map-3.13.0-58-generic
449 5825048 vmlinuz-3.13.0-58-generic.efi.signed
450 28304443 initrd.img-3.13.0-32-generic
451 =>
452
453The 'vmlinuz' files contain a packaged Linux kernel. The format is a kind of
454self-extracting compressed file mixed with some 'setup' configuration data.
455Despite its size (uncompressed it is >10MB) this only includes a basic set of
456device drivers, enough to boot on most hardware types.
457
458The 'initrd' files contain a RAM disk. This is something that can be loaded
459into RAM and will appear to Linux like a disk. Ubuntu uses this to hold lots
460of drivers for whatever hardware you might have. It is loaded before the
461real root disk is accessed.
462
463The numbers after the end of each file are the version. Here it is Linux
464version 3.13. You can find the source code for this in the Linux tree with
465the tag v3.13. The '.0' allows for additional Linux releases to fix problems,
466but normally this is not needed. The '-58' is used by Ubuntu. Each time they
467release a new kernel they increment this number. New Ubuntu versions might
468include kernel patches to fix reported bugs. Stable kernels can exist for
469some years so this number can get quite high.
470
471The '.efi.signed' kernel is signed for EFI's secure boot. U-Boot has its own
472secure boot mechanism - see [12] [13] and cannot read .efi files at present.
473
474To boot Ubuntu from U-Boot the steps are as follows:
475
4761. Set up the boot arguments. Use the GUID for the partition you want to
477boot:
478
479 => setenv bootargs root=/dev/disk/by-partuuid/965c59ee-1822-4326-90d2-b02446050059 ro
480
481Here root= tells Linux the location of its root disk. The disk is specified
482by its GUID, using '/dev/disk/by-partuuid/', a Linux path to a 'directory'
483containing all the GUIDs Linux has found. When it starts up, there will be a
484file in that directory with this name in it. It is also possible to use a
485device name here, see later.
486
4872. Load the kernel. Since it is an ext2/4 filesystem we can do:
488
489 => ext2load scsi 0:2 03000000 /boot/vmlinuz-3.13.0-58-generic
490
491The address 30000000 is arbitrary, but there seem to be problems with using
492small addresses (sometimes Linux cannot find the ramdisk). This is 48MB into
493the start of RAM (which is at 0 on x86).
494
4953. Load the ramdisk (to 64MB):
496
497 => ext2load scsi 0:2 04000000 /boot/initrd.img-3.13.0-58-generic
498
4994. Start up the kernel. We need to know the size of the ramdisk, but can use
500a variable for that. U-Boot sets 'filesize' to the size of the last file it
501loaded.
502
503 => zboot 03000000 0 04000000 ${filesize}
504
505Type 'help zboot' if you want to see what the arguments are. U-Boot on x86 is
506quite verbose when it boots a kernel. You should see these messages from
507U-Boot:
508
509 Valid Boot Flag
510 Setup Size = 0x00004400
511 Magic signature found
512 Using boot protocol version 2.0c
513 Linux kernel version 3.13.0-58-generic (buildd@allspice) #97-Ubuntu SMP Wed Jul 8 02:56:15 UTC 2015
514 Building boot_params at 0x00090000
515 Loading bzImage at address 100000 (5805728 bytes)
516 Magic signature found
517 Initial RAM disk at linear address 0x04000000, size 19215259 bytes
518 Kernel command line: "console=ttyS0,115200 root=/dev/disk/by-partuuid/965c59ee-1822-4326-90d2-b02446050059 ro"
519
520 Starting kernel ...
521
522U-Boot prints out some bootstage timing. This is more useful if you put the
523above commands into a script since then it will be faster.
524
525 Timer summary in microseconds:
526 Mark Elapsed Stage
527 0 0 reset
528 241,535 241,535 board_init_r
529 2,421,611 2,180,076 id=64
530 2,421,790 179 id=65
531 2,428,215 6,425 main_loop
532 48,860,584 46,432,369 start_kernel
533
534 Accumulated time:
535 240,329 ahci
536 1,422,704 vesa display
537
538Now the kernel actually starts:
539
540 [ 0.000000] Initializing cgroup subsys cpuset
541 [ 0.000000] Initializing cgroup subsys cpu
542 [ 0.000000] Initializing cgroup subsys cpuacct
543 [ 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)
544 [ 0.000000] Command line: console=ttyS0,115200 root=/dev/disk/by-partuuid/965c59ee-1822-4326-90d2-b02446050059 ro
545
546It continues for a long time. Along the way you will see it pick up your
547ramdisk:
548
549 [ 0.000000] RAMDISK: [mem 0x04000000-0x05253fff]
550...
551 [ 0.788540] Trying to unpack rootfs image as initramfs...
552 [ 1.540111] Freeing initrd memory: 18768K (ffff880004000000 - ffff880005254000)
553...
554
555Later it actually starts using it:
556
557 Begin: Running /scripts/local-premount ... done.
558
559You should also see your boot disk turn up:
560
561 [ 4.357243] scsi 1:0:0:0: Direct-Access ATA ADATA SP310 5.2 PQ: 0 ANSI: 5
562 [ 4.366860] sd 1:0:0:0: [sda] 62533296 512-byte logical blocks: (32.0 GB/29.8 GiB)
563 [ 4.375677] sd 1:0:0:0: Attached scsi generic sg0 type 0
564 [ 4.381859] sd 1:0:0:0: [sda] Write Protect is off
565 [ 4.387452] sd 1:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
566 [ 4.399535] sda: sda1 sda2 sda3
567
568Linux has found the three partitions (sda1-3). Mercifully it doesn't print out
569the GUIDs. In step 1 above we could have used:
570
571 setenv bootargs root=/dev/sda2 ro
572
573instead of the GUID. However if you add another drive to your board the
574numbering may change whereas the GUIDs will not. So if your boot partition
575becomes sdb2, it will still boot. For embedded systems where you just want to
576boot the first disk, you have that option.
577
578The last thing you will see on the console is mention of plymouth (which
579displays the Ubuntu start-up screen) and a lot of 'Starting' messages:
580
581 * Starting Mount filesystems on boot [ OK ]
582
583After a pause you should see a login screen on your display and you are done.
584
585If you want to put this in a script you can use something like this:
586
587 setenv bootargs root=UUID=b2aaf743-0418-4d90-94cc-3e6108d7d968 ro
588 setenv boot zboot 03000000 0 04000000 \${filesize}
589 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"
590 saveenv
591
592The \ is to tell the shell not to evaluate ${filesize} as part of the setenv
593command.
594
595You will also need to add this to your board configuration file, e.g.
596include/configs/minnowmax.h:
597
598 #define CONFIG_BOOTDELAY 2
599
600Now when you reset your board it wait a few seconds (in case you want to
601interrupt) and then should boot straight into Ubuntu.
602
603You can also bake this behaviour into your build by hard-coding the
604environment variables if you add this to minnowmax.h:
605
606#undef CONFIG_BOOTARGS
607#undef CONFIG_BOOTCOMMAND
608
609#define CONFIG_BOOTARGS \
610 "root=/dev/sda2 ro"
611#define CONFIG_BOOTCOMMAND \
612 "ext2load scsi 0:2 03000000 /boot/vmlinuz-3.13.0-58-generic; " \
613 "ext2load scsi 0:2 04000000 /boot/initrd.img-3.13.0-58-generic; " \
614 "run boot"
615
616#undef CONFIG_EXTRA_ENV_SETTINGS
617#define CONFIG_EXTRA_ENV_SETTINGS "boot=zboot 03000000 0 04000000 ${filesize}"
618
619
Simon Glass00bdd952015-01-27 22:13:46 -0700620Development Flow
621----------------
Simon Glass00bdd952015-01-27 22:13:46 -0700622These notes are for those who want to port U-Boot to a new x86 platform.
623
624Since x86 CPUs boot from SPI flash, a SPI flash emulator is a good investment.
625The Dediprog em100 can be used on Linux. The em100 tool is available here:
626
627 http://review.coreboot.org/p/em100.git
628
629On Minnowboard Max the following command line can be used:
630
631 sudo em100 -s -p LOW -d u-boot.rom -c W25Q64DW -r
632
633A suitable clip for connecting over the SPI flash chip is here:
634
635 http://www.dediprog.com/pd/programmer-accessories/EM-TC-8
636
637This allows you to override the SPI flash contents for development purposes.
638Typically you can write to the em100 in around 1200ms, considerably faster
639than programming the real flash device each time. The only important
640limitation of the em100 is that it only supports SPI bus speeds up to 20MHz.
641This means that images must be set to boot with that speed. This is an
642Intel-specific feature - e.g. tools/ifttool has an option to set the SPI
643speed in the SPI descriptor region.
644
645If your chip/board uses an Intel Firmware Support Package (FSP) it is fairly
646easy to fit it in. You can follow the Minnowboard Max implementation, for
647example. Hopefully you will just need to create new files similar to those
648in arch/x86/cpu/baytrail which provide Bay Trail support.
649
650If you are not using an FSP you have more freedom and more responsibility.
651The ivybridge support works this way, although it still uses a ROM for
652graphics and still has binary blobs containing Intel code. You should aim to
653support all important peripherals on your platform including video and storage.
654Use the device tree for configuration where possible.
655
656For the microcode you can create a suitable device tree file using the
657microcode tool:
658
Simon Glass03e3c312015-08-15 14:37:48 -0600659 ./tools/microcode-tool -d microcode.dat -m <model> create
Simon Glass00bdd952015-01-27 22:13:46 -0700660
661or if you only have header files and not the full Intel microcode.dat database:
662
663 ./tools/microcode-tool -H BAY_TRAIL_FSP_KIT/Microcode/M0130673322.h \
664 -H BAY_TRAIL_FSP_KIT/Microcode/M0130679901.h \
Simon Glass03e3c312015-08-15 14:37:48 -0600665 -m all create
Simon Glass00bdd952015-01-27 22:13:46 -0700666
667These are written to arch/x86/dts/microcode/ by default.
668
669Note that it is possible to just add the micrcode for your CPU if you know its
670model. U-Boot prints this information when it starts
671
672 CPU: x86_64, vendor Intel, device 30673h
673
674so here we can use the M0130673322 file.
675
676If you platform can display POST codes on two little 7-segment displays on
677the board, then you can use post_code() calls from C or assembler to monitor
678boot progress. This can be good for debugging.
679
680If not, you can try to get serial working as early as possible. The early
681debug serial port may be useful here. See setup_early_uart() for an example.
682
Bin Meng12c75102015-08-02 20:33:35 -0700683During the U-Boot porting, one of the important steps is to write correct PIRQ
684routing information in the board device tree. Without it, device drivers in the
685Linux kernel won't function correctly due to interrupt is not working. Please
686refer to U-Boot doc [14] for the device tree bindings of Intel interrupt router.
687Here we have more details on the intel,pirq-routing property below.
688
689 intel,pirq-routing = <
690 PCI_BDF(0, 2, 0) INTA PIRQA
691 ...
692 >;
693
694As you see each entry has 3 cells. For the first one, we need describe all pci
695devices mounted on the board. For SoC devices, normally there is a chapter on
696the chipset datasheet which lists all the available PCI devices. For example on
697Bay Trail, this is chapter 4.3 (PCI configuration space). For the second one, we
698can get the interrupt pin either from datasheet or hardware via U-Boot shell.
699The reliable source is the hardware as sometimes chipset datasheet is not 100%
700up-to-date. Type 'pci header' plus the device's pci bus/device/function number
701from U-Boot shell below.
702
703 => pci header 0.1e.1
704 vendor ID = 0x8086
705 device ID = 0x0f08
706 ...
707 interrupt line = 0x09
708 interrupt pin = 0x04
709 ...
710
711It shows this PCI device is using INTD pin as it reports 4 in the interrupt pin
712register. Repeat this until you get interrupt pins for all the devices. The last
713cell is the PIRQ line which a particular interrupt pin is mapped to. On Intel
714chipset, the power-up default mapping is INTA/B/C/D maps to PIRQA/B/C/D. This
715can be changed by registers in LPC bridge. So far Intel FSP does not touch those
716registers so we can write down the PIRQ according to the default mapping rule.
717
718Once we get the PIRQ routing information in the device tree, the interrupt
719allocation and assignment will be done by U-Boot automatically. Now you can
720enable CONFIG_GENERATE_PIRQ_TABLE for testing Linux kernel using i8259 PIC and
721CONFIG_GENERATE_MP_TABLE for testing Linux kernel using local APIC and I/O APIC.
722
Simon Glass590870e2015-08-13 10:36:17 -0600723This script might be useful. If you feed it the output of 'pci long' from
724U-Boot then it will generate a device tree fragment with the interrupt
725configuration for each device (note it needs gawk 4.0.0):
726
727 $ cat console_output |awk '/PCI/ {device=$4} /interrupt line/ {line=$4} \
728 /interrupt pin/ {pin = $4; if (pin != "0x00" && pin != "0xff") \
729 {patsplit(device, bdf, "[0-9a-f]+"); \
730 printf "PCI_BDF(%d, %d, %d) INT%c PIRQ%c\n", strtonum("0x" bdf[1]), \
731 strtonum("0x" bdf[2]), bdf[3], strtonum(pin) + 64, 64 + strtonum(pin)}}'
732
733Example output:
734 PCI_BDF(0, 2, 0) INTA PIRQA
735 PCI_BDF(0, 3, 0) INTA PIRQA
736...
737
Bin Meng448719c2015-09-09 23:20:29 -0700738Porting Hints
739-------------
740
741Quark-specific considerations:
742
743To port U-Boot to other boards based on the Intel Quark SoC, a few things need
744to be taken care of. The first important part is the Memory Reference Code (MRC)
745parameters. Quark MRC supports memory-down configuration only. All these MRC
746parameters are supplied via the board device tree. To get started, first copy
747the MRC section of arch/x86/dts/galileo.dts to your board's device tree, then
748change these values by consulting board manuals or your hardware vendor.
749Available MRC parameter values are listed in include/dt-bindings/mrc/quark.h.
750The other tricky part is with PCIe. Quark SoC integrates two PCIe root ports,
751but by default they are held in reset after power on. In U-Boot, PCIe
752initialization is properly handled as per Quark's firmware writer guide.
753In your board support codes, you need provide two routines to aid PCIe
754initialization, which are board_assert_perst() and board_deassert_perst().
755The two routines need implement a board-specific mechanism to assert/deassert
756PCIe PERST# pin. Care must be taken that in those routines that any APIs that
757may trigger PCI enumeration process are strictly forbidden, as any access to
758PCIe root port's configuration registers will cause system hang while it is
759held in reset. For more details, check how they are implemented by the Intel
760Galileo board support codes in board/intel/galileo/galileo.c.
761
Bin Meng5dad97e2014-12-17 15:50:48 +0800762TODO List
763---------
Bin Meng5dad97e2014-12-17 15:50:48 +0800764- Audio
765- Chrome OS verified boot
766- SMI and ACPI support, to provide platform info and facilities to Linux
767
768References
769----------
770[1] http://www.coreboot.org
Bin Meng1ae5b782015-05-07 21:34:12 +0800771[2] http://www.qemu.org
772[3] http://www.coreboot.org/~stepan/pci8086,0166.rom
773[4] http://www.intel.com/content/www/us/en/embedded/design-tools/evaluation-platforms/atom-e660-eg20t-development-kit.html
774[5] http://www.intel.com/fsp
Bin Meng7aaff9b2015-07-06 16:31:35 +0800775[6] http://www.intel.com/content/www/us/en/secure/intelligent-systems/privileged/e6xx-35-b1-cmc22211.html
776[7] http://www.ami.com/products/bios-uefi-tools-and-utilities/bios-uefi-utilities/
777[8] http://en.wikipedia.org/wiki/Microcode
778[9] http://simplefirmware.org
779[10] http://www.intel.com/design/archives/processors/pro/docs/242016.htm
Simon Glass7bea5272015-07-27 15:47:31 -0600780[11] https://en.wikipedia.org/wiki/GUID_Partition_Table
781[12] http://events.linuxfoundation.org/sites/events/files/slides/chromeos_and_diy_vboot_0.pdf
782[13] http://events.linuxfoundation.org/sites/events/files/slides/elce-2014.pdf
Bin Meng12c75102015-08-02 20:33:35 -0700783[14] doc/device-tree-bindings/misc/intel,irq-router.txt