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David Cantrell 07-13-2011 05:12 PM

Use xz compression on initrd.img, add back gfx firmware (#703914)
On 07/13/2011 12:53 PM, Will Woods wrote:

On Thu, 2011-07-07 at 13:32 -0400, David Cantrell wrote:

Use xz compression on the initrd.img file


+ (cd $MBD_DIR; find . |cpio --quiet -c -o) |xz -9> $MBD_FSIMAGE

This won't work, for two reasons:
1) If you're compressing initramfs with xz you *must* use the option
"--check=crc32" or the kernel won't be able to unpack it. (They also
recommend "--lzma2=dict=1MiB" but this isn't required.)
2) RHEL6-vintage kernels can't handle xz-compressed initramfs anyway.

However, they do lzma just fine, so this works:
[...] |xz -9 --format=lzma> $MBD_FSIMAGE
(I tested it in a VM to be sure).

File size difference from xz is negligible (4kb). I took the liberty of
fixing that line in rhel6-branch; hope that's OK.

Yes, that's fine. Thank you. I did not know you had to specify
--format=lzma or use --check=crc32 if you wanted to use the xz format.
I imagine these options are something we should monitor as I forsee the
defaults on them changing.

The goal with the bugfix wasn't to get xz compression specifically, just
to get better compression.

David Cantrell <>
Supervisor, Installer Engineering Team
Red Hat, Inc. | Westford, MA | EST5EDT

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