Chromium OS initramfs

Build logic for creating standalone initramfs environments.

See the README files in the respective subdirs for more details.

To Use

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).

To Make

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.

To Debug

It is possible to debug few of the initramfs targets in QEMU. Read test/README.md for more information.

Also, here is a shortcut for developing/debugging graphical bits in initramfs, without having to create a full image for every iteration.

After emerge-$BOARD, find your initramfs package from chroot /build/$BOARD/var/lib/initramfs and copy to a running DUT, for example /tmp/recovery_ramfs.cpio, then do followings on DUT over SSH:

1. mkdir /usr/local/test/; cd /usr/local/test
2. xzcat /tmp/XXXXXX_ramfs.cpio | toybox cpio -iv (Here we assume that the kernel is configured to use xz compression for its initramfs.)
3. stop ui; kill $(pidof frecon)
4. bind mount /dev, /proc, /sys and /tmp in /usr/local/test:

for d in dev proc sys tmp; do
   mount --bind /${d} /usr/local/test/${d}
done

5. chroot /usr/local/test /init
6. Iterate.