| .. SPDX-License-Identifier: GPL-2.0+ |
| .. sectionauthor:: Bin Meng <bmeng.cn@gmail.com> |
| |
| Coreboot |
| ======== |
| |
| 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:: |
| |
| $ make coreboot_defconfig |
| $ make all |
| |
| 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 0x1110000 |
| |
| Make sure 0x1110000 matches CONFIG_SYS_TEXT_BASE, which is the symbol address |
| of _x86boot_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. |
