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| -rw-r--r-- | doc/README.x86 | 32 |
1 files changed, 21 insertions, 11 deletions
diff --git a/doc/README.x86 b/doc/README.x86 index af2459c..9012541 100644 --- a/doc/README.x86 +++ b/doc/README.x86 @@ -18,15 +18,16 @@ U-Boot supports running as a coreboot [1] payload on x86. So far only Link 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'. +U-Boot also supports booting directly from x86 reset vector, without coreboot. +In this case, known as bare mode, from the fact that it runs on the +'bare metal', U-Boot acts like a BIOS replacement. 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 ------------------- +Build Instructions for U-Boot as coreboot payload +------------------------------------------------- Building U-Boot as a coreboot payload is just like building U-Boot for targets on other architectures, like below: @@ -48,6 +49,8 @@ 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. +Build Instructions for U-Boot as BIOS replacement (bare mode) +------------------------------------------------------------- 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 @@ -58,7 +61,9 @@ $ export BUILD_ROM=y This tells the Makefile to build u-boot.rom as a target. -Link-specific instructions: +--- + +Chromebook Link specific instructions for bare mode: First, you need the following binary blobs: @@ -87,7 +92,9 @@ Now you can build U-Boot and obtain u-boot.rom: $ make chromebook_link_defconfig $ make all -Intel Crown Bay specific instructions: +--- + +Intel Crown Bay specific instructions for bare mode: 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 @@ -122,7 +129,9 @@ Now you can build U-Boot and obtain u-boot.rom $ make crownbay_defconfig $ make all -Intel Minnowboard Max instructions: +--- + +Intel Minnowboard Max instructions for bare mode: 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 @@ -188,8 +197,9 @@ Offset Description Controlling config Overall ROM image size is controlled by CONFIG_ROM_SIZE. +--- -Intel Galileo instructions: +Intel Galileo instructions for bare mode: 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 @@ -252,8 +262,8 @@ 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 --------------- +Test with QEMU for bare mode +---------------------------- 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: |