Build logic for creating standalone initramfs environments.
See the README files in the respective subdirs for more details.
Normally you wouldn't build in this directory directly. Instead, you would build the chromeos-initramfs package with the right USE flags. e.g.:
$ USE=recovery_ramfs emerge-$BOARD chromeos-initramfs
That will install the cpio initramfs files into the sysroot for you to build into a kernel directly. The various build scripts would then be used to make the right kernel/image using those (e.g. mod_image_for_recovery.sh).
You could build these by hand for quick testing. Inside the chroot:
$ make SYSROOT=/build/$BOARD BOARD=$BOARD <target>
That will create the cpio archives for you.