[coreboot] Retrieving additional payload files from CBFS

[Trammell Hudson]

Is there an easy way for a running payload to extract additional files
from its CBFS image in ROM?  I'd like to have a reproducible kernel and
initrd as the primary payload, with user data (and keys) stored in a
separate payload section of the CBFS.

On the build host I can use cbfstool to add/extract them from the file,
but I'm not seeing an easy way to do it on the running machine
short of 'dd if=/dev/mem' at the correct address.