Trouble with vmlinuz (bzImage) but works with vmlinux (uncompressed)

[Loïc Minier]

        Hey folks

 I'm testing kexec on ARM under qemu-system-arm with a mach-versatile
 kernel (lightly patched).  kexec only works if I pass a vmlinux, but
 hangs if I pass a vmlinuz.  This sounds like an address computation
 issue to me.

 It would seem to me there are two issues here:
 - kexec-tools should work in both cases, perhaps the address
   computation is wrong when using a bzImage?
 - kexec-tools should uncompress the vmlinuz kernel into a vmlinux one
   before loading it as to allow skipping the "Uncompressing Linux..."
   step at kexec -e time -- would make the actual kernel switch a faster
   operation.

 What do you folks think?

 If people want to reproduce, kernel can be grabbed from:
    http://ports.ubuntu.com/ubuntu-ports/dists/lucid/main/installer-armel/current/images/versatile/netboot/
 you'll need some rootfs such as an Ubuntu lucid (10.04) armel
 userspace.  I'm using this kernel to start qemu and am converting it to
 vmlinux with the attached script.

 Instructions to reproduce are available in the Ubuntu bug where we
 track this at:
    https://bugs.launchpad.net/ubuntu/+source/linux/+bug/518567

    Thanks for your insights!

PS: is there a bug tracker for kexec?  I didn't find it in
http://bugzilla.kernel.org/enter_bug.cgi
-- 
Loïc Minier
-------------- next part --------------
#!/usr/bin/perl -n
# vmlinuz-to-vmlinux - uncompresses a bzImage kernel into a vmlinux one
# Copyright (C) 2010 Canonical Ltd
# Author: Loïc Minier <lool at dooz.org>
#
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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# DEALINGS IN THE SOFTWARE.
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# this Software without prior written authorization from the author.

use strict;
use warnings;

use IO::Uncompress::Gunzip qw(gunzip $GunzipError);

BEGIN { $/ = undef }

my $magic = pack 'H*', "1f8b0800";

s/.*?\Q$magic\E/$magic/s
    or die "Couldn't find magic bytes";

gunzip \$_ => \*STDOUT
    or die "gunzip failed: $GunzipError";