Pulling in fix for bug #140713 for Gutsy release
mdz at ubuntu.com
Fri Oct 12 10:09:56 BST 2007
It's up to the release managers whether this is worthwhile, though with
gfxboot being such a critical and hardware-dependent component, making a
change like this seems awfully risky at the 11th hour. It simply can't be
properly tested at this point.
On Thu, Oct 11, 2007 at 09:52:02AM -0500, Anthony Liguori wrote:
> Due to real mode usage in gfxboot, Ubuntu has never been able to install
> under KVM or Xen on Intel (VT) processors. The latest version of gfxboot
> attempted to fix this problem but there is a bug.
> A one-line fix is available that fixes the problem and allows Gutsy to be
> installed under KVM or Xen. The fix came from the gfxboot maintainer
> (Steffen Winterfeldt) and has gotten a lot of review on kvm-devel.
> While it is rather late to apply such a fix, the reward is great (allowing
> Gutsy to be used for open virtualization on Intel) and the risk is low
> since the patch has gotten a lot of review and is pretty obvious.
> I've included the patch in this email but the bug report should be
> consulted for more information around the patch.
> Sorry if this is the wrong place for such a request, I'm not that familiar
> with how things work in Ubuntu. The bug hasn't gotten much attention on
> launchpad and it's very important this is taken before the release of Gutsy
> (or it won't be useful until Gutsy+1).
> Anthony Liguori
> --- a/bincode.asm 2007-07-24 05:49:46.000000000 -0500
> +++ b/bincode.asm 2007-10-11 09:18:57.000000000 -0500
> @@ -15546,7 +15546,11 @@
> mov ax,pm_seg.prog_d16
> mov ds,ax
> - mov eax,ss
> + ; needed for KVM:
> + ; ss:rpl must equal cs:rpl in PM for VT. We can't rely on ss
> + ; maintaining its value after the transition.
> + movzx eax,word [rm_seg.ss]
> and esp,0ffffh
> shl eax,4
> add esp,eax
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