Hi, I've made some tests this night to reduce the size of 2.6 kernel. I've modularized almost all that can be (except IDE, mouse and keyboard). vmlinuz is now a bit less than 1.3 Megabytes. Compiling ext2 as a module would save us about 70 more kilobytes. ext2 module is 79k, cramfs takes 13k when builtin. A cramfs initrd is slightly larger than a ext2 initrd (about 2k).
So I patched mkinitrd and make-initrd to allow to build cramfs initrd.
(patchs included in this mail).
For now, the kernel can't load directly cramfs initrd (because the code
doesn't recognize cramfs magic number), but it can load gzipped cramfs
initrd (because the code can recognize a gzip file).
Well, a patch has been made (by Debian ?) and is included in Debian
kernel, but we don't care much since we can (theorically) load gzip
cramfs.
(I've extracted the patch from Debian's messy patch, it is
included too in this mail).
But when I try to boot with a gzipped cramfs initrd, the kernel
can gunzip the initrd but fails to mount it as ramfs,
sys_mount("/dev/root.old","/root","cramfs", ...) exits with EINVAL code.
Strangly enough, I can mount the initrd correctly once the kernel is
booted up (in this case, I use a ext2 initrd, ext2 and cramfs are
builtin).
Should I ask about it on lkml ?
--
Olivier Blin
mkinitrd.cramfs.patch
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make-initrd.cramfs.patch
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do_mounts_rd.c.cramfs.patch
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