2 files changed, 61 insertions, 0 deletions
diff --git a/roms/u-boot/doc/board/coreboot/coreboot.rst b/roms/u-boot/doc/board/coreboot/coreboot.rst
new file mode 100644
index 000000000..9c44c025a
--- /dev/null
+++ b/roms/u-boot/doc/board/coreboot/coreboot.rst
@@ -0,0 +1,52 @@
+.. 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.
+
+64-bit U-Boot
+-------------
+
+In addition to the 32-bit 'coreboot' build there is a 'coreboot64' build. This
+produces an image which can be booted from coreboot (32-bit). Internally it
+works by using a 32-bit SPL binary to switch to 64-bit for running U-Boot. It
+can be useful for running UEFI applications, for example.
+
+This has only been lightly tested.
diff --git a/roms/u-boot/doc/board/coreboot/index.rst b/roms/u-boot/doc/board/coreboot/index.rst
new file mode 100644
index 000000000..d148db95f
--- /dev/null
+++ b/roms/u-boot/doc/board/coreboot/index.rst
@@ -0,0 +1,9 @@
+.. SPDX-License-Identifier: GPL-2.0+
+
+Coreboot
+========
+
+.. toctree::
+   :maxdepth: 2
+
+   coreboot