diff options
Diffstat (limited to 'doc/README.x86')
| -rw-r--r-- | doc/README.x86 | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/doc/README.x86 b/doc/README.x86 new file mode 100644 index 0000000..5fab044 --- /dev/null +++ b/doc/README.x86 @@ -0,0 +1,126 @@ +# +# 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) has 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 and Intel Crown Bay board +support running U-Boot 'bare metal'. + +As for loading 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 + +Building 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 uncommenting the following line in the main U-Boot Makefile: + +# ALL-$(CONFIG_X86_RESET_VECTOR) += u-boot.rom + +Link-specific instructions: + +First, you need the following binary blobs: + +* descriptor.bin - Intel flash descriptor +* me.bin - Intel Management Engine +* mrc.bin - Memory Reference Code, which sets up SDRAM +* video ROM - sets up the display + +You can get these binary blobs by: + +$ 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-ivybridge.bin + +The 3rd one should be renamed to mrc.bin. +As for the video ROM, you can get it here [2]. +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 [3] relies on a binary blob called +Firmware Support Package [4] 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. + +Now you can build U-Boot and obtaim u-boot.rom + +$ make crownbay_defconfig +$ make all + +CPU Microcode +------------- +Modern CPU usually requires a special bit stream called microcode [5] 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. + +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 devie 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. + +TODO List +--------- +- MTRR support (for performance) +- 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.coreboot.org/~stepan/pci8086,0166.rom +[3] http://www.intel.com/content/www/us/en/embedded/design-tools/evaluation-platforms/atom-e660-eg20t-development-kit.html +[4] http://www.intel.com/fsp +[5] http://en.wikipedia.org/wiki/Microcode |