> Use unmkinitramfs. It appears you've only looked at the first archive, > the early one, which gets the kernel into shape. The second, main one > is the big one.
OK, for those interested I tracked it down: indeed the machine with the larger initrd had MODULES=most instead of MODULES=dep. It took me some effort to figure out that it was actually LZMA-compressed as I had specified (the first CPIO archive, containing the intel microcode blob isn't, but the second is): `unmkinitramfs` splits the initrd into separate CPIO archives but doesn't let you see them, so I could easily see the content of the archives but they were silently decompressed so you can't immediately see what compression (if any) is used. I had to tweak the code to preserve the intermediate temp files in order to get to the bottom of it. In any case, thanks all for the help, Stefan