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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
17(Chromebook Pixel) has been tested, but it should work with minimal adjustments
18on other x86 boards since coreboot deals with most of the low-level details.
19
20U-Boot also supports booting directly from x86 reset vector without coreboot,
Bin Meng67582c02015-02-04 16:26:14 +080021aka raw support or bare support. Currently Link, Intel Crown Bay, Intel
22Minnowboard Max and Intel Galileo support running U-Boot 'bare metal'.
Bin Meng5dad97e2014-12-17 15:50:48 +080023
Simon Glass3a1a18f2015-01-27 22:13:47 -070024As for loading an OS, U-Boot supports directly booting a 32-bit or 64-bit
25Linux kernel as part of a FIT image. It also supports a compressed zImage.
Bin Meng5dad97e2014-12-17 15:50:48 +080026
27Build Instructions
28------------------
29Building U-Boot as a coreboot payload is just like building U-Boot for targets
30on other architectures, like below:
31
32$ make coreboot-x86_defconfig
33$ make all
34
Bin Meng617b8672015-01-06 22:14:24 +080035Note this default configuration will build a U-Boot payload for the Link board.
36To build a coreboot payload against another board, you can change the build
37configuration during the 'make menuconfig' process.
38
39x86 architecture --->
40 ...
41 (chromebook_link) Board configuration file
42 (chromebook_link) Board Device Tree Source (dts) file
43 (0x19200000) Board specific Cache-As-RAM (CAR) address
44 (0x4000) Board specific Cache-As-RAM (CAR) size
45
46Change the 'Board configuration file' and 'Board Device Tree Source (dts) file'
47to point to a new board. You can also change the Cache-As-RAM (CAR) related
48settings here if the default values do not fit your new board.
49
Simon Glass3a1a18f2015-01-27 22:13:47 -070050Building a ROM version of U-Boot (hereafter referred to as u-boot.rom) is a
Bin Meng5dad97e2014-12-17 15:50:48 +080051little bit tricky, as generally it requires several binary blobs which are not
52shipped in the U-Boot source tree. Due to this reason, the u-boot.rom build is
53not turned on by default in the U-Boot source tree. Firstly, you need turn it
Simon Glasseea0f112015-01-27 22:13:32 -070054on by enabling the ROM build:
Bin Meng5dad97e2014-12-17 15:50:48 +080055
Simon Glasseea0f112015-01-27 22:13:32 -070056$ export BUILD_ROM=y
57
58This tells the Makefile to build u-boot.rom as a target.
Bin Meng5dad97e2014-12-17 15:50:48 +080059
60Link-specific instructions:
61
62First, you need the following binary blobs:
63
64* descriptor.bin - Intel flash descriptor
65* me.bin - Intel Management Engine
66* mrc.bin - Memory Reference Code, which sets up SDRAM
67* video ROM - sets up the display
68
69You can get these binary blobs by:
70
71$ git clone http://review.coreboot.org/p/blobs.git
72$ cd blobs
73
74Find the following files:
75
76* ./mainboard/google/link/descriptor.bin
77* ./mainboard/google/link/me.bin
Simon Glass8712af92015-04-19 22:05:37 -060078* ./northbridge/intel/sandybridge/systemagent-r6.bin
Bin Meng5dad97e2014-12-17 15:50:48 +080079
80The 3rd one should be renamed to mrc.bin.
81As for the video ROM, you can get it here [2].
82Make sure all these binary blobs are put in the board directory.
83
84Now you can build U-Boot and obtain u-boot.rom:
85
86$ make chromebook_link_defconfig
87$ make all
88
89Intel Crown Bay specific instructions:
90
91U-Boot support of Intel Crown Bay board [3] relies on a binary blob called
92Firmware Support Package [4] to perform all the necessary initialization steps
93as documented in the BIOS Writer Guide, including initialization of the CPU,
94memory controller, chipset and certain bus interfaces.
95
96Download the Intel FSP for Atom E6xx series and Platform Controller Hub EG20T,
97install it on your host and locate the FSP binary blob. Note this platform
98also requires a Chipset Micro Code (CMC) state machine binary to be present in
99the SPI flash where u-boot.rom resides, and this CMC binary blob can be found
100in this FSP package too.
101
102* ./FSP/QUEENSBAY_FSP_GOLD_001_20-DECEMBER-2013.fd
103* ./Microcode/C0_22211.BIN
104
105Rename the first one to fsp.bin and second one to cmc.bin and put them in the
106board directory.
107
Bin Meng83d97122015-03-05 11:21:03 +0800108Note the FSP release version 001 has a bug which could cause random endless
109loop during the FspInit call. This bug was published by Intel although Intel
110did not describe any details. We need manually apply the patch to the FSP
111binary using any hex editor (eg: bvi). Go to the offset 0x1fcd8 of the FSP
112binary, change the following five bytes values from orginally E8 42 FF FF FF
113to B8 00 80 0B 00.
114
Bin Meng617b8672015-01-06 22:14:24 +0800115Now you can build U-Boot and obtain u-boot.rom
Bin Meng5dad97e2014-12-17 15:50:48 +0800116
117$ make crownbay_defconfig
118$ make all
119
Simon Glass3a1a18f2015-01-27 22:13:47 -0700120Intel Minnowboard Max instructions:
121
122This uses as FSP as with Crown Bay, except it is for the Atom E3800 series.
123Download this and get the .fd file (BAYTRAIL_FSP_GOLD_003_16-SEP-2014.fd at
124the time of writing). Put it in the board directory:
125board/intel/minnowmax/fsp.bin
126
127Obtain the VGA RAM (Vga.dat at the time of writing) and put it into the same
128directory: board/intel/minnowmax/vga.bin
129
Simon Glass68522482015-04-25 11:46:43 -0600130You still need two more binary blobs. The first comes from the original
131firmware image available from:
132
133http://firmware.intel.com/sites/default/files/2014-WW42.4-MinnowBoardMax.73-64-bit.bin_Release.zip
134
135Unzip it:
136
137 $ unzip 2014-WW42.4-MinnowBoardMax.73-64-bit.bin_Release.zip
Simon Glass3a1a18f2015-01-27 22:13:47 -0700138
139Use ifdtool in the U-Boot tools directory to extract the images from that
140file, for example:
141
Simon Glass68522482015-04-25 11:46:43 -0600142 $ ./tools/ifdtool -x MNW2MAX1.X64.0073.R02.1409160934.bin
143
144This will provide the descriptor file - copy this into the correct place:
145
146 $ cp flashregion_0_flashdescriptor.bin board/intel/minnowmax/descriptor.bin
147
148Then do the same with the sample SPI image provided in the FSP (SPI.bin at
149the time of writing) to obtain the last image. Note that this will also
150produce a flash descriptor file, but it does not seem to work, probably
151because it is not designed for the Minnowmax. That is why you need to get
152the flash descriptor from the original firmware as above.
153
Simon Glass3a1a18f2015-01-27 22:13:47 -0700154 $ ./tools/ifdtool -x BayleyBay/SPI.bin
155 $ cp flashregion_2_intel_me.bin board/intel/minnowmax/me.bin
Simon Glass3a1a18f2015-01-27 22:13:47 -0700156
157Now you can build U-Boot and obtain u-boot.rom
158
159$ make minnowmax_defconfig
160$ make all
161
Bin Meng67582c02015-02-04 16:26:14 +0800162Intel Galileo instructions:
163
164Only one binary blob is needed for Remote Management Unit (RMU) within Intel
165Quark SoC. Not like FSP, U-Boot does not call into the binary. The binary is
166needed by the Quark SoC itself.
167
168You can get the binary blob from Quark Board Support Package from Intel website:
169
170* ./QuarkSocPkg/QuarkNorthCluster/Binary/QuarkMicrocode/RMU.bin
171
172Rename the file and put it to the board directory by:
173
174 $ cp RMU.bin board/intel/galileo/rmu.bin
175
176Now you can build U-Boot and obtain u-boot.rom
177
178$ make galileo_defconfig
179$ make all
Simon Glass3a1a18f2015-01-27 22:13:47 -0700180
Bin Meng617b8672015-01-06 22:14:24 +0800181Test with coreboot
182------------------
183For testing U-Boot as the coreboot payload, there are things that need be paid
184attention to. coreboot supports loading an ELF executable and a 32-bit plain
185binary, as well as other supported payloads. With the default configuration,
186U-Boot is set up to use a separate Device Tree Blob (dtb). As of today, the
187generated u-boot-dtb.bin needs to be packaged by the cbfstool utility (a tool
188provided by coreboot) manually as coreboot's 'make menuconfig' does not provide
189this capability yet. The command is as follows:
190
191# in the coreboot root directory
192$ ./build/util/cbfstool/cbfstool build/coreboot.rom add-flat-binary \
193 -f u-boot-dtb.bin -n fallback/payload -c lzma -l 0x1110000 -e 0x1110015
194
195Make sure 0x1110000 matches CONFIG_SYS_TEXT_BASE and 0x1110015 matches the
196symbol address of _start (in arch/x86/cpu/start.S).
197
198If you want to use ELF as the coreboot payload, change U-Boot configuration to
Simon Glasseea0f112015-01-27 22:13:32 -0700199use CONFIG_OF_EMBED instead of CONFIG_OF_SEPARATE.
Bin Meng617b8672015-01-06 22:14:24 +0800200
Simon Glass3a1a18f2015-01-27 22:13:47 -0700201To enable video you must enable these options in coreboot:
202
203 - Set framebuffer graphics resolution (1280x1024 32k-color (1:5:5))
204 - Keep VESA framebuffer
205
206At present it seems that for Minnowboard Max, coreboot does not pass through
207the video information correctly (it always says the resolution is 0x0). This
208works correctly for link though.
209
210
Bin Meng5dad97e2014-12-17 15:50:48 +0800211CPU Microcode
212-------------
Simon Glasseea0f112015-01-27 22:13:32 -0700213Modern CPUs usually require a special bit stream called microcode [5] to be
Bin Meng5dad97e2014-12-17 15:50:48 +0800214loaded on the processor after power up in order to function properly. U-Boot
215has already integrated these as hex dumps in the source tree.
216
217Driver Model
218------------
219x86 has been converted to use driver model for serial and GPIO.
220
221Device Tree
222-----------
223x86 uses device tree to configure the board thus requires CONFIG_OF_CONTROL to
Bin Meng617b8672015-01-06 22:14:24 +0800224be turned on. Not every device on the board is configured via device tree, but
Bin Meng5dad97e2014-12-17 15:50:48 +0800225more and more devices will be added as time goes by. Check out the directory
226arch/x86/dts/ for these device tree source files.
227
Simon Glasscb3b2e62015-01-01 16:18:15 -0700228Useful Commands
229---------------
230
231In keeping with the U-Boot philosophy of providing functions to check and
232adjust internal settings, there are several x86-specific commands that may be
233useful:
234
235hob - Display information about Firmware Support Package (FSP) Hand-off
236 Block. This is only available on platforms which use FSP, mostly
237 Atom.
238iod - Display I/O memory
239iow - Write I/O memory
240mtrr - List and set the Memory Type Range Registers (MTRR). These are used to
241 tell the CPU whether memory is cacheable and if so the cache write
242 mode to use. U-Boot sets up some reasonable values but you can
243 adjust then with this command.
244
Simon Glass00bdd952015-01-27 22:13:46 -0700245Development Flow
246----------------
Simon Glass00bdd952015-01-27 22:13:46 -0700247These notes are for those who want to port U-Boot to a new x86 platform.
248
249Since x86 CPUs boot from SPI flash, a SPI flash emulator is a good investment.
250The Dediprog em100 can be used on Linux. The em100 tool is available here:
251
252 http://review.coreboot.org/p/em100.git
253
254On Minnowboard Max the following command line can be used:
255
256 sudo em100 -s -p LOW -d u-boot.rom -c W25Q64DW -r
257
258A suitable clip for connecting over the SPI flash chip is here:
259
260 http://www.dediprog.com/pd/programmer-accessories/EM-TC-8
261
262This allows you to override the SPI flash contents for development purposes.
263Typically you can write to the em100 in around 1200ms, considerably faster
264than programming the real flash device each time. The only important
265limitation of the em100 is that it only supports SPI bus speeds up to 20MHz.
266This means that images must be set to boot with that speed. This is an
267Intel-specific feature - e.g. tools/ifttool has an option to set the SPI
268speed in the SPI descriptor region.
269
270If your chip/board uses an Intel Firmware Support Package (FSP) it is fairly
271easy to fit it in. You can follow the Minnowboard Max implementation, for
272example. Hopefully you will just need to create new files similar to those
273in arch/x86/cpu/baytrail which provide Bay Trail support.
274
275If you are not using an FSP you have more freedom and more responsibility.
276The ivybridge support works this way, although it still uses a ROM for
277graphics and still has binary blobs containing Intel code. You should aim to
278support all important peripherals on your platform including video and storage.
279Use the device tree for configuration where possible.
280
281For the microcode you can create a suitable device tree file using the
282microcode tool:
283
284 ./tools/microcode-tool -d microcode.dat create <model>
285
286or if you only have header files and not the full Intel microcode.dat database:
287
288 ./tools/microcode-tool -H BAY_TRAIL_FSP_KIT/Microcode/M0130673322.h \
289 -H BAY_TRAIL_FSP_KIT/Microcode/M0130679901.h \
290 create all
291
292These are written to arch/x86/dts/microcode/ by default.
293
294Note that it is possible to just add the micrcode for your CPU if you know its
295model. U-Boot prints this information when it starts
296
297 CPU: x86_64, vendor Intel, device 30673h
298
299so here we can use the M0130673322 file.
300
301If you platform can display POST codes on two little 7-segment displays on
302the board, then you can use post_code() calls from C or assembler to monitor
303boot progress. This can be good for debugging.
304
305If not, you can try to get serial working as early as possible. The early
306debug serial port may be useful here. See setup_early_uart() for an example.
307
Bin Meng5dad97e2014-12-17 15:50:48 +0800308TODO List
309---------
Bin Meng5dad97e2014-12-17 15:50:48 +0800310- Audio
311- Chrome OS verified boot
312- SMI and ACPI support, to provide platform info and facilities to Linux
313
314References
315----------
316[1] http://www.coreboot.org
317[2] http://www.coreboot.org/~stepan/pci8086,0166.rom
318[3] http://www.intel.com/content/www/us/en/embedded/design-tools/evaluation-platforms/atom-e660-eg20t-development-kit.html
319[4] http://www.intel.com/fsp
320[5] http://en.wikipedia.org/wiki/Microcode