Some device firmware, such as the graphics microcontroller, is needed
during the initrd - i915 is often loaded in the initrd, and this is the
only chance to load GuC firmware.
Device firmware must still be available after the real root is mounted
too, so update the custom firmware path in the kernel when the firmware
is moved to /run.
Signed-off-by: Jonathon Hall <jonathon.hall@puri.sm>
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>
Blob jail provides device firmware blobs to the OS, so the OS does not
have to ship them. The firmware is passed through the initrd to
/run/firmware, so it works with both installed and live OSes, and there
are no race conditions between firmware load and firmware availability.
The injection method in the initrd is specific to the style of init
script used by PureOS, since it must add a copy command to copy the
firmware from the initrd to /run. If the init script is not of this
type, boot proceeds without device firmware.
This feature can be enabled or disabled from the config GUI.
Blob jail is enabled automatically if the Intel AX200 Wi-Fi module is
installed and the feature hasn't been explicitly configured.
Signed-off-by: Matt DeVillier <matt.devillier@puri.sm>
