x86: Update README.x86 for QEMU support
Document how to build and test U-Boot with QEMU. Signed-off-by: Bin Meng <bmeng.cn@gmail.com> Acked-by: Simon Glass <sjg@chromium.org>utp
Bin Meng
Simon Glass
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b28c147569
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1ae5b78c45
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@ -14,12 +14,13 @@ including supported boards, build instructions, todo list, etc.
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Status
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------
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U-Boot supports running as a coreboot [1] payload on x86. So far only Link
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(Chromebook Pixel) has been tested, but it should work with minimal adjustments
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on other x86 boards since coreboot deals with most of the low-level details.
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(Chromebook Pixel) and QEMU [2] x86 targets have been tested, but it should
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work with minimal adjustments on other x86 boards since coreboot deals with
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most of the low-level details.
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U-Boot also supports booting directly from x86 reset vector without coreboot,
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aka raw support or bare support. Currently Link, Intel Crown Bay, Intel
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Minnowboard Max and Intel Galileo support running U-Boot 'bare metal'.
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aka raw support or bare support. Currently Link, QEMU x86 targets and all
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Intel boards support running U-Boot 'bare metal'.
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As for loading an OS, U-Boot supports directly booting a 32-bit or 64-bit
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Linux kernel as part of a FIT image. It also supports a compressed zImage.
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@ -32,15 +33,15 @@ on other architectures, like below:
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$ make coreboot-x86_defconfig
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$ make all
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Note this default configuration will build a U-Boot payload for the Link board.
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Note this default configuration will build a U-Boot payload for the QEMU board.
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To build a coreboot payload against another board, you can change the build
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configuration during the 'make menuconfig' process.
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x86 architecture --->
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...
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(chromebook_link) Board configuration file
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(chromebook_link) Board Device Tree Source (dts) file
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(0x19200000) Board specific Cache-As-RAM (CAR) address
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(qemu-x86) Board configuration file
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(qemu-x86) Board Device Tree Source (dts) file
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(0x01920000) Board specific Cache-As-RAM (CAR) address
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(0x4000) Board specific Cache-As-RAM (CAR) size
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Change the 'Board configuration file' and 'Board Device Tree Source (dts) file'
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@ -78,7 +79,7 @@ Find the following files:
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* ./northbridge/intel/sandybridge/systemagent-r6.bin
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The 3rd one should be renamed to mrc.bin.
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As for the video ROM, you can get it here [2].
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As for the video ROM, you can get it here [3].
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Make sure all these binary blobs are put in the board directory.
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Now you can build U-Boot and obtain u-boot.rom:
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@ -88,8 +89,8 @@ $ make all
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Intel Crown Bay specific instructions:
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U-Boot support of Intel Crown Bay board [3] relies on a binary blob called
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Firmware Support Package [4] to perform all the necessary initialization steps
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U-Boot support of Intel Crown Bay board [4] relies on a binary blob called
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Firmware Support Package [5] to perform all the necessary initialization steps
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as documented in the BIOS Writer Guide, including initialization of the CPU,
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memory controller, chipset and certain bus interfaces.
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@ -178,6 +179,13 @@ Now you can build U-Boot and obtain u-boot.rom
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$ make galileo_defconfig
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$ make all
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QEMU x86 target instructions:
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To build u-boot.rom for QEMU x86 targets, just simply run
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$ make qemu-x86_defconfig
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$ make all
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Test with coreboot
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------------------
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For testing U-Boot as the coreboot payload, there are things that need be paid
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@ -207,10 +215,33 @@ At present it seems that for Minnowboard Max, coreboot does not pass through
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the video information correctly (it always says the resolution is 0x0). This
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works correctly for link though.
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Test with QEMU
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--------------
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QEMU is a fancy emulator that can enable us to test U-Boot without access to
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a real x86 board. To launch QEMU with u-boot.rom, call QEMU as follows:
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$ qemu-system-i386 -nographic -bios path/to/u-boot.rom
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This will instantiate an emulated x86 board with i440FX and PIIX chipset. QEMU
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also supports emulating an x86 board with Q35 and ICH9 based chipset, which is
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also supported by U-Boot. To instantiate such a machine, call QEMU with:
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$ qemu-system-i386 -nographic -bios path/to/u-boot.rom -M q35
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Note by default QEMU instantiated boards only have 128 MiB system memory. But
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it is enough to have U-Boot boot and function correctly. You can increase the
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system memory by pass '-m' parameter to QEMU if you want more memory:
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$ qemu-system-i386 -nographic -bios path/to/u-boot.rom -m 1024
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This creates a board with 1 GiB system memory. Currently U-Boot for QEMU only
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supports 3 GiB maximum system memory and reserves the last 1 GiB address space
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for PCI device memory-mapped I/O and other stuff, so the maximum value of '-m'
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would be 3072.
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CPU Microcode
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-------------
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Modern CPUs usually require a special bit stream called microcode [5] to be
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Modern CPUs usually require a special bit stream called microcode [6] to be
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loaded on the processor after power up in order to function properly. U-Boot
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has already integrated these as hex dumps in the source tree.
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@ -227,7 +258,6 @@ arch/x86/dts/ for these device tree source files.
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Useful Commands
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---------------
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In keeping with the U-Boot philosophy of providing functions to check and
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adjust internal settings, there are several x86-specific commands that may be
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useful:
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@ -314,7 +344,8 @@ TODO List
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References
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----------
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[1] http://www.coreboot.org
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[2] http://www.coreboot.org/~stepan/pci8086,0166.rom
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[3] http://www.intel.com/content/www/us/en/embedded/design-tools/evaluation-platforms/atom-e660-eg20t-development-kit.html
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[4] http://www.intel.com/fsp
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[5] http://en.wikipedia.org/wiki/Microcode
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[2] http://www.qemu.org
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[3] http://www.coreboot.org/~stepan/pci8086,0166.rom
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[4] http://www.intel.com/content/www/us/en/embedded/design-tools/evaluation-platforms/atom-e660-eg20t-development-kit.html
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[5] http://www.intel.com/fsp
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[6] http://en.wikipedia.org/wiki/Microcode
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