I'm using clonezilla-1.2.12 and need to add the Broadcom firmware to the initrd so it can netboot.
(clonezilla is debian-based and debian no longer includes the firmware blobs as they're non-free. Naturally then clonezilla doesn't either.)
(I can't use the Ubuntu-based clonezilla as Ubuntu has a bug in it where the Broadcom 5708 chipset Just Doesn't Work.)
I have what seems like a good process for doing so:
~# mkdir /tmp/cz-newinitrd
~# cd /tmp/cz-newinitrd
/tmp/cz-newinitrd# xzcat /media/CLONEZILLA/live/initrd.img.orig > initrd
/tmp/cz-newinitrd# (cd /; find lib/firmware/bnx2 | cpio -o -H newc --append -O /tmp/cz-newinitrd/initrd)
/tmp/cz-newinitrd# xz -c initrd > /media/CLONEZILLA/live/initrd.img
BUT linux refuses to recognize the redone initrd:

I also tried making a single cpio archive (without using --append) and got the same result.
If I completely skip modifying the archive and just uncompress/recompress I still get the same result.
What is going wrong here?