The code in here will help you test out the various initramfs environments in a QEMU VM. This way you don't have to generate the image, write it to a USB stick, and then boot it on a real device.
Caveat: This stuff might have rough edges.
You must first run ./build_packages for the board you want to test. Most likely that means amd64-generic.
You must run this inside the chroot.
Use the test.sh script in here to compile the initramfs rootfs, kernel, disk image, and qemu wrapper script to test each environment out.
Artifacts will be placed in the typical ~/trunk/src/build/initramfs/ tree. In there you‘ll find a directory for each target. In there you’ll find all the relevant files and a helper qemu script. Run that to boot the system.
GUI: Not required, can be tested via command line (as the console will be via an emulated serial port).
Disk images: factory_shim is simply a bootstrap loader that runs anything in the chromiumos_image_usb.bin so you will want to copy a real factory installer image (build_image factory_install) for it. For example,
cp ~/trunk/src/build/images/$BOARD/latest/factory_install_shim.bin \ ~/trunk/src/build/initramfs/factory_shim/chromiumos_image_usb.bin
factory_shim).