Rationale:
cpio -t alone cannot extract initrd past early cpio (microcode) in most packed initrd.
unpack_initramfs.sh already under master comes to the rescue, but its usage up to today was limited to pass firmware blobs to final OS under boards/librem_mini_v2
Debian OSes (and probably others) need to have cryptroot/crypttab overriden directly, otherwise generic generation of crypttab is not enough.
Extracting crypttab and overriding directly what is desired by final OS and exposed into /boot/initrd is the way to go otherwise hacking on top of hacks.
This brings default packed modules under Heads to 5 modules, which needs to be deactivate in board configs if undesired:
user@heads-tests-deb12:~/heads$ grep -Rn "?= y" modules/ | grep -v MUSL
modules/zlib:1:CONFIG_ZLIB ?= y
modules/zstd:3:CONFIG_ZSTD ?= y
modules/exfatprogs:2:CONFIG_EXFATPROGS ?= y
modules/busybox:2:CONFIG_BUSYBOX ?= y
modules/e2fsprogs:2:CONFIG_E2FSPROGS ?= y
Debian 12's initrd by default now consists of an uncompressed cpio
archive containing microcode, followed by a zstd-compressed cpio
archive. inject_firmware.sh only supported gzip-compressed cpio, so it
could not extract /init from this archive.
Add zstd-decompress to decompress zstd streams (uncompressed size is
about 180 KB).
Add unpack_initramfs.sh which is able to decompress uncompressed, gzip,
or zstd archives, with multiple segments, much like the Linux kernel
itself does.
Use unpack_initramfs.sh to extract /init for blob jail.
Don't compress the new archive segment containing firmware and the
updated /init.
Signed-off-by: Jonathon Hall <jonathon.hall@puri.sm>
