doc/README.x86 - filogic/uboot - Gitiles

 #
 # Copyright (C) 2014, Simon Glass <sjg@chromium.org>
 # Copyright (C) 2014, Bin Meng <bmeng.cn@gmail.com>
 #
 # SPDX-License-Identifier:	GPL-2.0+
 #

 U-Boot on x86
 =============

 This document describes the information about U-Boot running on x86 targets,
 including supported boards, build instructions, todo list, etc.

 Status
 ------
 U-Boot supports running as a coreboot [1] payload on x86. So far only Link
 (Chromebook Pixel) and QEMU [2] x86 targets have been tested, but it should
 work with minimal adjustments on other x86 boards since coreboot deals with
 most of the low-level details.

 U-Boot also supports booting directly from x86 reset vector without coreboot,
 aka raw support or bare support. Currently Link, QEMU x86 targets and all
 Intel boards support running U-Boot 'bare metal'.

 As for loading an OS, U-Boot supports directly booting a 32-bit or 64-bit
 Linux kernel as part of a FIT image. It also supports a compressed zImage.

 Build Instructions
 ------------------
 Building U-Boot as a coreboot payload is just like building U-Boot for targets
 on other architectures, like below:

 $ make coreboot-x86_defconfig
 $ make all

 Note this default configuration will build a U-Boot payload for the QEMU board.
 To build a coreboot payload against another board, you can change the build
 configuration during the 'make menuconfig' process.

 x86 architecture  --->
 	...
 	(qemu-x86) Board configuration file
 	(qemu-x86_i440fx) Board Device Tree Source (dts) file
 	(0x01920000) Board specific Cache-As-RAM (CAR) address
 	(0x4000) Board specific Cache-As-RAM (CAR) size

 Change the 'Board configuration file' and 'Board Device Tree Source (dts) file'
 to point to a new board. You can also change the Cache-As-RAM (CAR) related
 settings here if the default values do not fit your new board.

 Building a ROM version of U-Boot (hereafter referred to as u-boot.rom) is a
 little bit tricky, as generally it requires several binary blobs which are not
 shipped in the U-Boot source tree. Due to this reason, the u-boot.rom build is
 not turned on by default in the U-Boot source tree. Firstly, you need turn it
 on by enabling the ROM build:

 $ export BUILD_ROM=y

 This tells the Makefile to build u-boot.rom as a target.

 Link-specific instructions:

 First, you need the following binary blobs:

 * descriptor.bin - Intel flash descriptor
 * me.bin - Intel Management Engine
 * mrc.bin - Memory Reference Code, which sets up SDRAM
 * video ROM - sets up the display

 You can get these binary blobs by:

 $ git clone http://review.coreboot.org/p/blobs.git
 $ cd blobs

 Find the following files:

 * ./mainboard/google/link/descriptor.bin
 * ./mainboard/google/link/me.bin
 * ./northbridge/intel/sandybridge/systemagent-r6.bin

 The 3rd one should be renamed to mrc.bin.
 As for the video ROM, you can get it here [3] and rename it to vga.bin.
 Make sure all these binary blobs are put in the board directory.

 Now you can build U-Boot and obtain u-boot.rom:

 $ make chromebook_link_defconfig
 $ make all

 Intel Crown Bay specific instructions:

 U-Boot support of Intel Crown Bay board [4] relies on a binary blob called
 Firmware Support Package [5] to perform all the necessary initialization steps
 as documented in the BIOS Writer Guide, including initialization of the CPU,
 memory controller, chipset and certain bus interfaces.

 Download the Intel FSP for Atom E6xx series and Platform Controller Hub EG20T,
 install it on your host and locate the FSP binary blob. Note this platform
 also requires a Chipset Micro Code (CMC) state machine binary to be present in
 the SPI flash where u-boot.rom resides, and this CMC binary blob can be found
 in this FSP package too.

 * ./FSP/QUEENSBAY_FSP_GOLD_001_20-DECEMBER-2013.fd
 * ./Microcode/C0_22211.BIN

 Rename the first one to fsp.bin and second one to cmc.bin and put them in the
 board directory.

 Note the FSP release version 001 has a bug which could cause random endless
 loop during the FspInit call. This bug was published by Intel although Intel
 did not describe any details. We need manually apply the patch to the FSP
 binary using any hex editor (eg: bvi). Go to the offset 0x1fcd8 of the FSP
 binary, change the following five bytes values from orginally E8 42 FF FF FF
 to B8 00 80 0B 00.

 As for the video ROM, you need manually extract it from the Intel provided
 BIOS for Crown Bay here [6], using the AMI MMTool [7]. Check PCI option ROM
 ID 8086:4108, extract and save it as vga.bin in the board directory.

 Now you can build U-Boot and obtain u-boot.rom

 $ make crownbay_defconfig
 $ make all

 Intel Minnowboard Max instructions:

 This uses as FSP as with Crown Bay, except it is for the Atom E3800 series.
 Download this and get the .fd file (BAYTRAIL_FSP_GOLD_003_16-SEP-2014.fd at
 the time of writing). Put it in the board directory:
 board/intel/minnowmax/fsp.bin

 Obtain the VGA RAM (Vga.dat at the time of writing) and put it into the same
 directory: board/intel/minnowmax/vga.bin

 You still need two more binary blobs. The first comes from the original
 firmware image available from:

 http://firmware.intel.com/sites/default/files/2014-WW42.4-MinnowBoardMax.73-64-bit.bin_Release.zip

 Unzip it:

    $ unzip 2014-WW42.4-MinnowBoardMax.73-64-bit.bin_Release.zip

 Use ifdtool in the U-Boot tools directory to extract the images from that
 file, for example:

    $ ./tools/ifdtool -x MNW2MAX1.X64.0073.R02.1409160934.bin

 This will provide the descriptor file - copy this into the correct place:

    $ cp flashregion_0_flashdescriptor.bin board/intel/minnowmax/descriptor.bin

 Then do the same with the sample SPI image provided in the FSP (SPI.bin at
 the time of writing) to obtain the last image. Note that this will also
 produce a flash descriptor file, but it does not seem to work, probably
 because it is not designed for the Minnowmax. That is why you need to get
 the flash descriptor from the original firmware as above.

    $ ./tools/ifdtool -x BayleyBay/SPI.bin
    $ cp flashregion_2_intel_me.bin board/intel/minnowmax/me.bin

 Now you can build U-Boot and obtain u-boot.rom

 $ make minnowmax_defconfig
 $ make all

 Intel Galileo instructions:

 Only one binary blob is needed for Remote Management Unit (RMU) within Intel
 Quark SoC. Not like FSP, U-Boot does not call into the binary. The binary is
 needed by the Quark SoC itself.

 You can get the binary blob from Quark Board Support Package from Intel website:

 * ./QuarkSocPkg/QuarkNorthCluster/Binary/QuarkMicrocode/RMU.bin

 Rename the file and put it to the board directory by:

    $ cp RMU.bin board/intel/galileo/rmu.bin

 Now you can build U-Boot and obtain u-boot.rom

 $ make galileo_defconfig
 $ make all

 QEMU x86 target instructions:

 To build u-boot.rom for QEMU x86 targets, just simply run

 $ make qemu-x86_defconfig
 $ make all

 Note this default configuration will build a U-Boot for the QEMU x86 i440FX
 board. To build a U-Boot against QEMU x86 Q35 board, you can change the build
 configuration during the 'make menuconfig' process like below:

 Device Tree Control  --->
 	...
 	(qemu-x86_q35) Default Device Tree for DT control

 Test with coreboot
 ------------------
 For testing U-Boot as the coreboot payload, there are things that need be paid
 attention to. coreboot supports loading an ELF executable and a 32-bit plain
 binary, as well as other supported payloads. With the default configuration,
 U-Boot is set up to use a separate Device Tree Blob (dtb). As of today, the
 generated u-boot-dtb.bin needs to be packaged by the cbfstool utility (a tool
 provided by coreboot) manually as coreboot's 'make menuconfig' does not provide
 this capability yet. The command is as follows:

 # in the coreboot root directory
 $ ./build/util/cbfstool/cbfstool build/coreboot.rom add-flat-binary \
   -f u-boot-dtb.bin -n fallback/payload -c lzma -l 0x1110000 -e 0x1110015

 Make sure 0x1110000 matches CONFIG_SYS_TEXT_BASE and 0x1110015 matches the
 symbol address of _start (in arch/x86/cpu/start.S).

 If you want to use ELF as the coreboot payload, change U-Boot configuration to
 use CONFIG_OF_EMBED instead of CONFIG_OF_SEPARATE.

 To enable video you must enable these options in coreboot:

    - Set framebuffer graphics resolution (1280x1024 32k-color (1:5:5))
    - Keep VESA framebuffer

 At present it seems that for Minnowboard Max, coreboot does not pass through
 the video information correctly (it always says the resolution is 0x0). This
 works correctly for link though.

 Test with QEMU
 --------------
 QEMU is a fancy emulator that can enable us to test U-Boot without access to
 a real x86 board. Please make sure your QEMU version is 2.3.0 or above test
 U-Boot. To launch QEMU with u-boot.rom, call QEMU as follows:

 $ qemu-system-i386 -nographic -bios path/to/u-boot.rom

 This will instantiate an emulated x86 board with i440FX and PIIX chipset. QEMU
 also supports emulating an x86 board with Q35 and ICH9 based chipset, which is
 also supported by U-Boot. To instantiate such a machine, call QEMU with:

 $ qemu-system-i386 -nographic -bios path/to/u-boot.rom -M q35

 Note by default QEMU instantiated boards only have 128 MiB system memory. But
 it is enough to have U-Boot boot and function correctly. You can increase the
 system memory by pass '-m' parameter to QEMU if you want more memory:

 $ qemu-system-i386 -nographic -bios path/to/u-boot.rom -m 1024

 This creates a board with 1 GiB system memory. Currently U-Boot for QEMU only
 supports 3 GiB maximum system memory and reserves the last 1 GiB address space
 for PCI device memory-mapped I/O and other stuff, so the maximum value of '-m'
 would be 3072.

 QEMU emulates a graphic card which U-Boot supports. Removing '-nographic' will
 show QEMU's VGA console window. Note this will disable QEMU's serial output.
 If you want to check both consoles, use '-serial stdio'.

 CPU Microcode
 -------------
 Modern CPUs usually require a special bit stream called microcode [8] to be
 loaded on the processor after power up in order to function properly. U-Boot
 has already integrated these as hex dumps in the source tree.

 SMP Support
 -----------
 On a multicore system, U-Boot is executed on the bootstrap processor (BSP).
 Additional application processors (AP) can be brought up by U-Boot. In order to
 have an SMP kernel to discover all of the available processors, U-Boot needs to
 prepare configuration tables which contain the multi-CPUs information before
 loading the OS kernel. Currently U-Boot supports generating two types of tables
 for SMP, called Simple Firmware Interface (SFI) [9] and Multi-Processor (MP)
 [10] tables. The writing of these two tables are controlled by two Kconfig
 options GENERATE_SFI_TABLE and GENERATE_MP_TABLE.

 Driver Model
 ------------
 x86 has been converted to use driver model for serial and GPIO.

 Device Tree
 -----------
 x86 uses device tree to configure the board thus requires CONFIG_OF_CONTROL to
 be turned on. Not every device on the board is configured via device tree, but
 more and more devices will be added as time goes by. Check out the directory
 arch/x86/dts/ for these device tree source files.

 Useful Commands
 ---------------
 In keeping with the U-Boot philosophy of providing functions to check and
 adjust internal settings, there are several x86-specific commands that may be
 useful:

 hob  - Display information about Firmware Support Package (FSP) Hand-off
 	 Block. This is only available on platforms which use FSP, mostly
 	 Atom.
 iod  - Display I/O memory
 iow  - Write I/O memory
 mtrr - List and set the Memory Type Range Registers (MTRR). These are used to
 	 tell the CPU whether memory is cacheable and if so the cache write
 	 mode to use. U-Boot sets up some reasonable values but you can
 	 adjust then with this command.

 Development Flow
 ----------------
 These notes are for those who want to port U-Boot to a new x86 platform.

 Since x86 CPUs boot from SPI flash, a SPI flash emulator is a good investment.
 The Dediprog em100 can be used on Linux. The em100 tool is available here:

    http://review.coreboot.org/p/em100.git

 On Minnowboard Max the following command line can be used:

    sudo em100 -s -p LOW -d u-boot.rom -c W25Q64DW -r

 A suitable clip for connecting over the SPI flash chip is here:

    http://www.dediprog.com/pd/programmer-accessories/EM-TC-8

 This allows you to override the SPI flash contents for development purposes.
 Typically you can write to the em100 in around 1200ms, considerably faster
 than programming the real flash device each time. The only important
 limitation of the em100 is that it only supports SPI bus speeds up to 20MHz.
 This means that images must be set to boot with that speed. This is an
 Intel-specific feature - e.g. tools/ifttool has an option to set the SPI
 speed in the SPI descriptor region.

 If your chip/board uses an Intel Firmware Support Package (FSP) it is fairly
 easy to fit it in. You can follow the Minnowboard Max implementation, for
 example. Hopefully you will just need to create new files similar to those
 in arch/x86/cpu/baytrail which provide Bay Trail support.

 If you are not using an FSP you have more freedom and more responsibility.
 The ivybridge support works this way, although it still uses a ROM for
 graphics and still has binary blobs containing Intel code. You should aim to
 support all important peripherals on your platform including video and storage.
 Use the device tree for configuration where possible.

 For the microcode you can create a suitable device tree file using the
 microcode tool:

   ./tools/microcode-tool -d microcode.dat create <model>

 or if you only have header files and not the full Intel microcode.dat database:

   ./tools/microcode-tool -H BAY_TRAIL_FSP_KIT/Microcode/M0130673322.h \
 	-H BAY_TRAIL_FSP_KIT/Microcode/M0130679901.h \
 	create all

 These are written to arch/x86/dts/microcode/ by default.

 Note that it is possible to just add the micrcode for your CPU if you know its
 model. U-Boot prints this information when it starts

    CPU: x86_64, vendor Intel, device 30673h

 so here we can use the M0130673322 file.

 If you platform can display POST codes on two little 7-segment displays on
 the board, then you can use post_code() calls from C or assembler to monitor
 boot progress. This can be good for debugging.

 If not, you can try to get serial working as early as possible. The early
 debug serial port may be useful here. See setup_early_uart() for an example.

 TODO List
 ---------
 - Audio
 - Chrome OS verified boot
 - SMI and ACPI support, to provide platform info and facilities to Linux

 References
 ----------
 [1] http://www.coreboot.org
 [2] http://www.qemu.org
 [3] http://www.coreboot.org/~stepan/pci8086,0166.rom
 [4] http://www.intel.com/content/www/us/en/embedded/design-tools/evaluation-platforms/atom-e660-eg20t-development-kit.html
 [5] http://www.intel.com/fsp
 [6] http://www.intel.com/content/www/us/en/secure/intelligent-systems/privileged/e6xx-35-b1-cmc22211.html
 [7] http://www.ami.com/products/bios-uefi-tools-and-utilities/bios-uefi-utilities/
 [8] http://en.wikipedia.org/wiki/Microcode
 [9] http://simplefirmware.org
 [10] http://www.intel.com/design/archives/processors/pro/docs/242016.htm
	#
	# Copyright (C) 2014, Simon Glass <sjg@chromium.org>
	# Copyright (C) 2014, Bin Meng <bmeng.cn@gmail.com>
	#
	# SPDX-License-Identifier: GPL-2.0+
	#

	U-Boot on x86
	=============

	This document describes the information about U-Boot running on x86 targets,
	including supported boards, build instructions, todo list, etc.

	Status
	------
	U-Boot supports running as a coreboot [1] payload on x86. So far only Link
	(Chromebook Pixel) and QEMU [2] x86 targets have been tested, but it should
	work with minimal adjustments on other x86 boards since coreboot deals with
	most of the low-level details.

	U-Boot also supports booting directly from x86 reset vector without coreboot,
	aka raw support or bare support. Currently Link, QEMU x86 targets and all
	Intel boards support running U-Boot 'bare metal'.

	As for loading an OS, U-Boot supports directly booting a 32-bit or 64-bit
	Linux kernel as part of a FIT image. It also supports a compressed zImage.

	Build Instructions
	------------------
	Building U-Boot as a coreboot payload is just like building U-Boot for targets
	on other architectures, like below:

	$ make coreboot-x86_defconfig
	$ make all

	Note this default configuration will build a U-Boot payload for the QEMU board.
	To build a coreboot payload against another board, you can change the build
	configuration during the 'make menuconfig' process.

	x86 architecture --->
	...
	(qemu-x86) Board configuration file
	(qemu-x86_i440fx) Board Device Tree Source (dts) file
	(0x01920000) Board specific Cache-As-RAM (CAR) address
	(0x4000) Board specific Cache-As-RAM (CAR) size

	Change the 'Board configuration file' and 'Board Device Tree Source (dts) file'
	to point to a new board. You can also change the Cache-As-RAM (CAR) related
	settings here if the default values do not fit your new board.

	Building a ROM version of U-Boot (hereafter referred to as u-boot.rom) is a
	little bit tricky, as generally it requires several binary blobs which are not
	shipped in the U-Boot source tree. Due to this reason, the u-boot.rom build is
	not turned on by default in the U-Boot source tree. Firstly, you need turn it
	on by enabling the ROM build:

	$ export BUILD_ROM=y

	This tells the Makefile to build u-boot.rom as a target.

	Link-specific instructions:

	First, you need the following binary blobs:

	* descriptor.bin - Intel flash descriptor
	* me.bin - Intel Management Engine
	* mrc.bin - Memory Reference Code, which sets up SDRAM
	* video ROM - sets up the display

	You can get these binary blobs by:

	$ git clone http://review.coreboot.org/p/blobs.git
	$ cd blobs

	Find the following files:

	* ./mainboard/google/link/descriptor.bin
	* ./mainboard/google/link/me.bin
	* ./northbridge/intel/sandybridge/systemagent-r6.bin

	The 3rd one should be renamed to mrc.bin.
	As for the video ROM, you can get it here [3] and rename it to vga.bin.
	Make sure all these binary blobs are put in the board directory.

	Now you can build U-Boot and obtain u-boot.rom:

	$ make chromebook_link_defconfig
	$ make all

	Intel Crown Bay specific instructions:

	U-Boot support of Intel Crown Bay board [4] relies on a binary blob called
	Firmware Support Package [5] to perform all the necessary initialization steps
	as documented in the BIOS Writer Guide, including initialization of the CPU,
	memory controller, chipset and certain bus interfaces.

	Download the Intel FSP for Atom E6xx series and Platform Controller Hub EG20T,
	install it on your host and locate the FSP binary blob. Note this platform
	also requires a Chipset Micro Code (CMC) state machine binary to be present in
	the SPI flash where u-boot.rom resides, and this CMC binary blob can be found
	in this FSP package too.

	* ./FSP/QUEENSBAY_FSP_GOLD_001_20-DECEMBER-2013.fd
	* ./Microcode/C0_22211.BIN

	Rename the first one to fsp.bin and second one to cmc.bin and put them in the
	board directory.

	Note the FSP release version 001 has a bug which could cause random endless
	loop during the FspInit call. This bug was published by Intel although Intel
	did not describe any details. We need manually apply the patch to the FSP
	binary using any hex editor (eg: bvi). Go to the offset 0x1fcd8 of the FSP
	binary, change the following five bytes values from orginally E8 42 FF FF FF
	to B8 00 80 0B 00.

	As for the video ROM, you need manually extract it from the Intel provided
	BIOS for Crown Bay here [6], using the AMI MMTool [7]. Check PCI option ROM
	ID 8086:4108, extract and save it as vga.bin in the board directory.

	Now you can build U-Boot and obtain u-boot.rom

	$ make crownbay_defconfig
	$ make all

	Intel Minnowboard Max instructions:

	This uses as FSP as with Crown Bay, except it is for the Atom E3800 series.
	Download this and get the .fd file (BAYTRAIL_FSP_GOLD_003_16-SEP-2014.fd at
	the time of writing). Put it in the board directory:
	board/intel/minnowmax/fsp.bin

	Obtain the VGA RAM (Vga.dat at the time of writing) and put it into the same
	directory: board/intel/minnowmax/vga.bin

	You still need two more binary blobs. The first comes from the original
	firmware image available from:

	http://firmware.intel.com/sites/default/files/2014-WW42.4-MinnowBoardMax.73-64-bit.bin_Release.zip

	Unzip it:

	$ unzip 2014-WW42.4-MinnowBoardMax.73-64-bit.bin_Release.zip

	Use ifdtool in the U-Boot tools directory to extract the images from that
	file, for example:

	$ ./tools/ifdtool -x MNW2MAX1.X64.0073.R02.1409160934.bin

	This will provide the descriptor file - copy this into the correct place:

	$ cp flashregion_0_flashdescriptor.bin board/intel/minnowmax/descriptor.bin

	Then do the same with the sample SPI image provided in the FSP (SPI.bin at
	the time of writing) to obtain the last image. Note that this will also
	produce a flash descriptor file, but it does not seem to work, probably
	because it is not designed for the Minnowmax. That is why you need to get
	the flash descriptor from the original firmware as above.

	$ ./tools/ifdtool -x BayleyBay/SPI.bin
	$ cp flashregion_2_intel_me.bin board/intel/minnowmax/me.bin

	Now you can build U-Boot and obtain u-boot.rom

	$ make minnowmax_defconfig
	$ make all

	Intel Galileo instructions:

	Only one binary blob is needed for Remote Management Unit (RMU) within Intel
	Quark SoC. Not like FSP, U-Boot does not call into the binary. The binary is
	needed by the Quark SoC itself.

	You can get the binary blob from Quark Board Support Package from Intel website:

	* ./QuarkSocPkg/QuarkNorthCluster/Binary/QuarkMicrocode/RMU.bin

	Rename the file and put it to the board directory by:

	$ cp RMU.bin board/intel/galileo/rmu.bin

	Now you can build U-Boot and obtain u-boot.rom

	$ make galileo_defconfig
	$ make all

	QEMU x86 target instructions:

	To build u-boot.rom for QEMU x86 targets, just simply run

	$ make qemu-x86_defconfig
	$ make all

	Note this default configuration will build a U-Boot for the QEMU x86 i440FX
	board. To build a U-Boot against QEMU x86 Q35 board, you can change the build
	configuration during the 'make menuconfig' process like below:

	Device Tree Control --->
	...
	(qemu-x86_q35) Default Device Tree for DT control

	Test with coreboot
	------------------
	For testing U-Boot as the coreboot payload, there are things that need be paid
	attention to. coreboot supports loading an ELF executable and a 32-bit plain
	binary, as well as other supported payloads. With the default configuration,
	U-Boot is set up to use a separate Device Tree Blob (dtb). As of today, the
	generated u-boot-dtb.bin needs to be packaged by the cbfstool utility (a tool
	provided by coreboot) manually as coreboot's 'make menuconfig' does not provide
	this capability yet. The command is as follows:

	# in the coreboot root directory
	$ ./build/util/cbfstool/cbfstool build/coreboot.rom add-flat-binary \
	-f u-boot-dtb.bin -n fallback/payload -c lzma -l 0x1110000 -e 0x1110015

	Make sure 0x1110000 matches CONFIG_SYS_TEXT_BASE and 0x1110015 matches the
	symbol address of _start (in arch/x86/cpu/start.S).

	If you want to use ELF as the coreboot payload, change U-Boot configuration to
	use CONFIG_OF_EMBED instead of CONFIG_OF_SEPARATE.

	To enable video you must enable these options in coreboot:

	- Set framebuffer graphics resolution (1280x1024 32k-color (1:5:5))
	- Keep VESA framebuffer

	At present it seems that for Minnowboard Max, coreboot does not pass through
	the video information correctly (it always says the resolution is 0x0). This
	works correctly for link though.

	Test with QEMU
	--------------
	QEMU is a fancy emulator that can enable us to test U-Boot without access to
	a real x86 board. Please make sure your QEMU version is 2.3.0 or above test
	U-Boot. To launch QEMU with u-boot.rom, call QEMU as follows:

	$ qemu-system-i386 -nographic -bios path/to/u-boot.rom

	This will instantiate an emulated x86 board with i440FX and PIIX chipset. QEMU
	also supports emulating an x86 board with Q35 and ICH9 based chipset, which is
	also supported by U-Boot. To instantiate such a machine, call QEMU with:

	$ qemu-system-i386 -nographic -bios path/to/u-boot.rom -M q35

	Note by default QEMU instantiated boards only have 128 MiB system memory. But
	it is enough to have U-Boot boot and function correctly. You can increase the
	system memory by pass '-m' parameter to QEMU if you want more memory:

	$ qemu-system-i386 -nographic -bios path/to/u-boot.rom -m 1024

	This creates a board with 1 GiB system memory. Currently U-Boot for QEMU only
	supports 3 GiB maximum system memory and reserves the last 1 GiB address space
	for PCI device memory-mapped I/O and other stuff, so the maximum value of '-m'
	would be 3072.

	QEMU emulates a graphic card which U-Boot supports. Removing '-nographic' will
	show QEMU's VGA console window. Note this will disable QEMU's serial output.
	If you want to check both consoles, use '-serial stdio'.

	CPU Microcode
	-------------
	Modern CPUs usually require a special bit stream called microcode [8] to be
	loaded on the processor after power up in order to function properly. U-Boot
	has already integrated these as hex dumps in the source tree.

	SMP Support
	-----------
	On a multicore system, U-Boot is executed on the bootstrap processor (BSP).
	Additional application processors (AP) can be brought up by U-Boot. In order to
	have an SMP kernel to discover all of the available processors, U-Boot needs to
	prepare configuration tables which contain the multi-CPUs information before
	loading the OS kernel. Currently U-Boot supports generating two types of tables
	for SMP, called Simple Firmware Interface (SFI) [9] and Multi-Processor (MP)
	[10] tables. The writing of these two tables are controlled by two Kconfig
	options GENERATE_SFI_TABLE and GENERATE_MP_TABLE.

	Driver Model
	------------
	x86 has been converted to use driver model for serial and GPIO.

	Device Tree
	-----------
	x86 uses device tree to configure the board thus requires CONFIG_OF_CONTROL to
	be turned on. Not every device on the board is configured via device tree, but
	more and more devices will be added as time goes by. Check out the directory
	arch/x86/dts/ for these device tree source files.

	Useful Commands
	---------------
	In keeping with the U-Boot philosophy of providing functions to check and
	adjust internal settings, there are several x86-specific commands that may be
	useful:

	hob - Display information about Firmware Support Package (FSP) Hand-off
	Block. This is only available on platforms which use FSP, mostly
	Atom.
	iod - Display I/O memory
	iow - Write I/O memory
	mtrr - List and set the Memory Type Range Registers (MTRR). These are used to
	tell the CPU whether memory is cacheable and if so the cache write
	mode to use. U-Boot sets up some reasonable values but you can
	adjust then with this command.

	Development Flow
	----------------
	These notes are for those who want to port U-Boot to a new x86 platform.

	Since x86 CPUs boot from SPI flash, a SPI flash emulator is a good investment.
	The Dediprog em100 can be used on Linux. The em100 tool is available here:

	http://review.coreboot.org/p/em100.git

	On Minnowboard Max the following command line can be used:

	sudo em100 -s -p LOW -d u-boot.rom -c W25Q64DW -r

	A suitable clip for connecting over the SPI flash chip is here:

	http://www.dediprog.com/pd/programmer-accessories/EM-TC-8

	This allows you to override the SPI flash contents for development purposes.
	Typically you can write to the em100 in around 1200ms, considerably faster
	than programming the real flash device each time. The only important
	limitation of the em100 is that it only supports SPI bus speeds up to 20MHz.
	This means that images must be set to boot with that speed. This is an
	Intel-specific feature - e.g. tools/ifttool has an option to set the SPI
	speed in the SPI descriptor region.

	If your chip/board uses an Intel Firmware Support Package (FSP) it is fairly
	easy to fit it in. You can follow the Minnowboard Max implementation, for
	example. Hopefully you will just need to create new files similar to those
	in arch/x86/cpu/baytrail which provide Bay Trail support.

	If you are not using an FSP you have more freedom and more responsibility.
	The ivybridge support works this way, although it still uses a ROM for
	graphics and still has binary blobs containing Intel code. You should aim to
	support all important peripherals on your platform including video and storage.
	Use the device tree for configuration where possible.

	For the microcode you can create a suitable device tree file using the
	microcode tool:

	./tools/microcode-tool -d microcode.dat create <model>

	or if you only have header files and not the full Intel microcode.dat database:

	./tools/microcode-tool -H BAY_TRAIL_FSP_KIT/Microcode/M0130673322.h \
	-H BAY_TRAIL_FSP_KIT/Microcode/M0130679901.h \
	create all

	These are written to arch/x86/dts/microcode/ by default.

	Note that it is possible to just add the micrcode for your CPU if you know its
	model. U-Boot prints this information when it starts

	CPU: x86_64, vendor Intel, device 30673h

	so here we can use the M0130673322 file.

	If you platform can display POST codes on two little 7-segment displays on
	the board, then you can use post_code() calls from C or assembler to monitor
	boot progress. This can be good for debugging.

	If not, you can try to get serial working as early as possible. The early
	debug serial port may be useful here. See setup_early_uart() for an example.

	TODO List
	---------
	- Audio
	- Chrome OS verified boot
	- SMI and ACPI support, to provide platform info and facilities to Linux

	References
	----------
	[1] http://www.coreboot.org
	[2] http://www.qemu.org
	[3] http://www.coreboot.org/~stepan/pci8086,0166.rom
	[4] http://www.intel.com/content/www/us/en/embedded/design-tools/evaluation-platforms/atom-e660-eg20t-development-kit.html
	[5] http://www.intel.com/fsp
	[6] http://www.intel.com/content/www/us/en/secure/intelligent-systems/privileged/e6xx-35-b1-cmc22211.html
	[7] http://www.ami.com/products/bios-uefi-tools-and-utilities/bios-uefi-utilities/
	[8] http://en.wikipedia.org/wiki/Microcode
	[9] http://simplefirmware.org
	[10] http://www.intel.com/design/archives/processors/pro/docs/242016.htm