Documentation: Bring back abuild documentation

Based on contents from coreboot wiki[1], this patch adds much needed
documentation for the very important abuild utility.

On top of what was there:
- Mainboard targets have been updated
- Added example for building one variant of one board
- Added example for building boards selectively and/or with custom
  configurations using --skip_set/--skip_unset, -K, and config files

[1] https://www.coreboot.org/Abuild

Change-Id: I69701eaeef616828bc30736aba2f617e844a3148
Signed-off-by: Keith Hui <buurin@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/76775
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Singer <service+coreboot-gerrit@felixsinger.de>

2 files changed, 261 insertions, 0 deletions

diff --git a/Documentation/util/abuild/index.md b/Documentation/util/abuild/index.md
new file mode 100644
index 000000000000..4def2f6a49fa
--- /dev/null
+++ b/Documentation/util/abuild/index.md
@@ -0,0 +1,260 @@
+abuild
+======
+
+This utility is a great tool to check whether your coreboot tree
+compiles for one or all targets. It compiles the 'default' build for a
+mainboard. This is roughly equivalent to removing the .config file,
+running `make menuconfig`, selecting the manufacturer and mainboard,
+then saving the config without making any other changes.
+
+It is run on all patches submitted via gerrit as part of the process.
+Before submitting a patch, it is a very good idea to run abuild first
+to make sure your patch compiles cleanly for all.
+
+Note that abuild is a tool to do a simple build test, and binaries it
+produces may well not boot if flashed to a system.
+
+### Basic usage
+
+abuild needs to be run from the coreboot directory. If you cd into the
+coreboot/util/abuild directory and try to run it from there, it will
+not run correctly.
+
+If you invoke abuild with no parameters, it will build all boards
+automatically.
+
+You can also specify a single board to build with the -t option. For
+example, to build the Lenovo X230 target, run:
+
+```bash
+$ util/abuild/abuild -t lenovo/x230
+```
+
+### Where builds and logs are stored
+
+The resulting images and logs are stored in directory coreboot-builds/
+under your current directory. This can be overridden with --outdir:
+
+```bash
+$ util/abuild/abuild --outdir /mnt/portable/coreboot-builds
+```
+
+This is useful if you want to divert the build to an external hard
+drive, e.g. to keep the solid-state drive holding the coreboot tree
+young.
+
+(We will still refer to this directory as "coreboot-builds" below.)
+
+After running the X230 build above, the build log will be in
+coreboot-builds/LENOVO_X230/make.log.
+
+For an overview of what passed and what failed, look at
+coreboot-builds/passing_boards and coreboot-builds/failing_boards.
+**These logs are overwritten with each abuild run.** Save them elsewhere
+if you feel a need to reference the results later.
+
+### Payloads
+
+You can also specify a payload directory with -p:
+
+```bash
+mkdir payloads
+cp /somewhere/filo.elf payloads
+```
+
+Then add a file payloads/payload.sh which prints the name of the
+payload to use (and takes the mainboard as a parameter) such as:
+
+```bash
+echo "`dirname $0`/build/filo.elf"
+```
+
+Then you can build an image with payload by specifying:
+
+```bash
+util/abuild/abuild -t lenovo/x230 -p ./payloads
+```
+
+You can also tell abuild not to use a payload:
+
+```bash
+util/abuild/abuild -t lenovo/x230 -p none
+```
+
+### Build non-default configurations
+
+Sometimes you do need to build test a custom, non-default configuration.
+This can be accomplished by placing a config file in configs/.
+
+First, clean your slate with `make distclean` or `rm .config`.
+
+Then run `make menuconfig`, select the manufacturer and mainboard, and
+configure the options you need to test building for.
+
+Then save a minimal config file omitting options that did not change
+from default:
+
+```bash
+make savedefconfig
+```
+
+This file is saved as `defconfig` and can be edited further.
+
+Now this file can be saved in configs/ which will form the basis of a
+custom configuration included in an abuild. However, it needs to be
+named in a specific way for abuild to pick it up:
+
+```
+config.<board>_<suffix>
+```
+
+<board> is effectively the BOARD\_xxx Kconfig option without "BOARD\_".
+<suffix> is a free form description of the configuration being built.
+
+For example, a config for ASUS P8Z77-M PRO that tests building with MRC
+raminit code (as opposed to the default native raminit) would be named
+`config.asus_p8z77_m_pro_mrc_bin` and contains:
+
+```
+CONFIG_VENDOR_ASUS=y
+CONFIG_BOARD_ASUS_P8Z77_M_PRO=y
+# CONFIG_USE_NATIVE_RAMINIT is not set
+CONFIG_CPU_MICROCODE_CBFS_NONE=y
+# CONFIG_BOOTBLOCK_CONSOLE is not set
+# CONFIG_POSTCAR_CONSOLE is not set
+```
+
+For what we are trying to do, not setting USE_NATIVE_RAMINIT is the
+important part. The other three optional changes are meant to speed
+things up. All these options can be selected during `make menuconfig`.
+
+Path to MRC binary blob remains default and thus not included here.
+
+Custom configurations can also be put in a file and applied to an entire
+abuild run using -K. Assume for example you are not interested in
+the postcar stage at all and just want it to shut up, you can create
+a file named `myconfig` with this line:
+
+```
+# CONFIG_POSTCAR_CONSOLE is not set
+```
+
+and run `abuild -K myconfig` to build everything with a silent postcar
+stage.
+
+### Selectively build certain targets only (also config file naming caveats)
+
+The P8Z77-M PRO example above would fail for P8Z77-M, because the
+config file name is ambiguous. `abuild` would pick up this config when
+building for P8Z77-M, but fails when it sees that this config isn't
+meant for P8Z77-M (but for P8Z77-M PRO). To avoid this error, you have
+to skip this config using --skip_set:
+
+```bash
+util/abuild/abuild --skip_set BOARD_ASUS_P8Z77_M_PRO
+```
+
+To complete the test, run abuild again specifically for this board
+variant (see next section).
+
+You can skip building other targets based on other Kconfigs. To skip
+building targets without a Kconfig set, use --skip_unset:
+
+```bash
+util/abuild/abuild --skip_unset USE_NATIVE_RAMINIT
+```
+This example skips building configs not using (Sandy/Ivy Bridge) native
+RAM init.
+
+### Additional Examples
+
+Many boards have multiple variants. You can build for a specific
+variant of a board:
+
+```bash
+util/abuild/abuild -t asus/p8x7x-series -b p8z77-m_pro -p none
+```
+
+Many of the boards need files from the 'blobs' repository, which will
+be initialized by the -B option. If the blobs repo has already been
+initialized in your local tree, it won't hurt to add the -B.
+
+```bash
+util/abuild/abuild -B -t lenovo/x230 -p none
+```
+
+Adding ccache to your system and telling abuild to use it with the -y
+option will speed things up a bit:
+
+```bash
+util/abuild/abuild -B -y -t lenovo/x230 -p none
+```
+
+Telling abuild to use multiple cores with the -c option helps speed
+things up as well:
+
+```bash
+util/abuild/abuild -B -y -c 8 -t lenovo/x230 -p none
+```
+
+Of course, the real power of abuild is in testing multiple boards.
+
+```bash
+util/abuild/abuild -B -y -c 8 -p none
+```
+
+### Full options list
+
+```text
+coreboot autobuild v0.11.01 (Feb 3, 2023)
+[...]
+Usage: util/abuild/abuild [options]
+       util/abuild/abuild [-V|--version]
+       util/abuild/abuild [-h|--help]
+
+Options:
+    [-a|--all]                    Build previously succeeded ports as well
+    [-A|--any-toolchain]          Use any toolchain
+    [-b|--board-variant <name>]   Build specific board variant under the
+                                  given target.
+    [-B|--blobs]                  Allow using binary files
+    [--checksum <path/basefile>]  Store checksums at path/basefile
+    [-c|--cpus <numcpus>]         Build on <numcpus> at the same time
+    [-C|--config]                 Configure-only mode
+    [-d|--dir <dir>]              Directory containing config files
+    [-e|--exitcode]               Exit with a non-zero errorlevel on failure
+    [-J|--junit]                  Write JUnit formatted xml log file
+    [-K|--kconfig <name>]         Prepend file to generated Kconfig
+    [-l|--loglevel <num>]         Set loglevel
+    [-L|--clang]                  Use clang on supported arch
+    [-n|--name]                   Set build name - also sets xmlfile if not
+                                  already set
+    [-o|--outdir <path>]          Store build results in path
+                                  (defaults to coreboot-builds)
+    [-p|--payloads <dir>]         Use payloads in <dir> to build images
+    [-P|--prefix <name>]          File name prefix in CBFS
+    [-q|--quiet]                  Print fewer messages
+    [-r|--remove]                 Remove output dir after build
+    [-R|--root <path>]            Absolute path to coreboot sources
+                                  (defaults to /usr/src/coreboot)
+    [--scan-build]                Use clang's static analyzer
+    [--skip_set <value>]          Skip building boards with this Kconfig set
+    [--skip_unset <value>]        Skip building boards with this Kconfig not set
+    [--timeless]                  Generate timeless builds
+    [-t|--target <vendor/board>]  Attempt to build target vendor/board only
+    [-T|--test]                   Submit image(s) to automated test system
+    [-u|--update]                 Update existing image
+    [-v|--verbose]                Print more messages
+    [-x|--chromeos]               Build with CHROMEOS enabled
+                                  Skip boards without ChromeOS support
+    [-X|--xmlfile <name>]         Set JUnit XML log file filename
+                                  (defaults to /usr/src/coreboot/abuild.xml)
+    [-y|--ccache]                 Use ccache
+    [-z|--clean]                  Remove build results when finished
+    [-Z|--clean-somewhat]         Remove build but keep coreboot.rom + config
+
+    [-V|--version]                Print version number and exit
+    [-h|--help]                   Print this help and exit
+
+    [-s|--silent]                 obsolete
+```
diff --git a/util/util_readme/post_util.md b/util/util_readme/post_util.md
index 9533cb192aac..78519ad14c85 100644
--- a/util/util_readme/post_util.md
+++ b/util/util_readme/post_util.md
@@ -1,5 +1,6 @@
 ## In depth documentation
 
+* [abuild](util/abuild/index.md)
 * [cbfstool](util/cbfstool/index.md)
 * [ifdtool](util/ifdtool/index.md)
 * [intelp2m](util/intelp2m/index.md)