win7 guest boot up fail.

[chao zhou]

Environment:
------------
Host OS (ia32/ia32e/IA64):ia32e
Guest OS (ia32/ia32e/IA64):ia32e
Guest OS Type (Linux/Windows):windows
kvm.git Commit:d6d63b51fe3bfea0cf596993afa480b0b3b02c32
qemu.git Commit:a1d22a367d5780c9553b2cd5a24f665534ce6ed6
Host Kernel Version:3.13.0-rc1
Hardware:Romley_EP, Ivytown_EP

Bug detailed description:
--------------------------
when create a win7 guest, the guest boot up fail.

note:
1. when create win2k3, win2k8 guest, the guest boot up fail.
2. when create win8, win2012 guest, the guest boot up fine.
3. this should be a qemu bug
kvm + qemu = result
d6d63b51 + a1d22a36 = bad
d6d63b51 + 7dc65c02 = good

Reproduce steps:
----------------
1. create guest
qemu-system-x86_64 -enable-kvm -m 1024 -smp 2 -net none /root/win7.img

Current result:
----------------
win7 guest boot up fail

Expected result:
----------------
win7 guest boot up fine

Basic root-causing log:
----------------------

[chao zhou (chao-zhou)]

the first bad commit is:
commit 6eefccc0bb9c34051b1e21880fc3a1c1c8686edd
Author: Gerd Hoffmann <email address hidden>
Date: Mon Dec 2 13:01:20 2013 +0100

    roms: update vgabios binaries

    This also switches from lgplvgabios to seavgabios.

    Signed-off-by: Gerd Hoffmann <email address hidden>

[Paolo Bonzini (bonzini)]

Already reported http://permalink.gmane.org/gmane.comp.emulators.qemu/245664

[chao zhou (chao-zhou)]

kvm.git + qemu.git: d3714010 + d844a7b6
after create win7 guest, the guest boots up fine