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

---

Changes in v2: None

doc/README.x86 | 65 +++++++++++++++++++++++++++++++++++++++++++--------------- 1 file changed, 48 insertions(+), 17 deletions(-)

diff --git a/doc/README.x86 b/doc/README.x86 index ef13fb4..4a30f68 100644 --- a/doc/README.x86 +++ b/doc/README.x86 @@ -14,12 +14,13 @@ 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) has been tested, but it should work with minimal adjustments -on other x86 boards since coreboot deals with most of the low-level details. +(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, Intel Crown Bay, Intel -Minnowboard Max and Intel Galileo support running U-Boot 'bare metal'. +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. @@ -32,15 +33,15 @@ on other architectures, like below: $ make coreboot-x86_defconfig $ make all

-Note this default configuration will build a U-Boot payload for the Link board. +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 ---> ... - (chromebook_link) Board configuration file - (chromebook_link) Board Device Tree Source (dts) file - (0x19200000) Board specific Cache-As-RAM (CAR) address + (qemu-x86) Board configuration file + (qemu-x86) 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' @@ -78,7 +79,7 @@ Find the following files: * ./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 [2]. +As for the video ROM, you can get it here [3]. Make sure all these binary blobs are put in the board directory.

Now you can build U-Boot and obtain u-boot.rom: @@ -88,8 +89,8 @@ $ make all

Intel Crown Bay specific instructions:

-U-Boot support of Intel Crown Bay board [3] relies on a binary blob called -Firmware Support Package [4] to perform all the necessary initialization steps +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.

@@ -178,6 +179,13 @@ 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 + Test with coreboot ------------------ For testing U-Boot as the coreboot payload, there are things that need be paid @@ -207,10 +215,33 @@ 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. 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.

CPU Microcode ------------- -Modern CPUs usually require a special bit stream called microcode [5] to be +Modern CPUs usually require a special bit stream called microcode [6] 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.

@@ -227,7 +258,6 @@ 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: @@ -314,7 +344,8 @@ TODO List References ---------- [1] http://www.coreboot.org -[2] http://www.coreboot.org/~stepan/pci8086,0166.rom -[3] http://www.intel.com/content/www/us/en/embedded/design-tools/evaluation-plat... -[4] http://www.intel.com/fsp -[5] http://en.wikipedia.org/wiki/Microcode +[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-plat... +[5] http://www.intel.com/fsp +[6] http://en.wikipedia.org/wiki/Microcode