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Date: Mon, 28 Nov 2011 12:00:47 -0200
From: Luiz Capitulino <lcapitulino@redhat.com>
Message-ID: <20111128120047.7e00ef15@doriath>
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Subject: Re: [Qemu-devel] [BUG 1.0] -cpu host breaks linux guest boot
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To: Anthony Liguori <anthony@codemonkey.ws>
Cc: Avi Kivity <avi@redhat.com>, qemu-devel <qemu-devel@nongnu.org>

On Sun, 27 Nov 2011 11:13:59 -0600
Anthony Liguori <anthony@codemonkey.ws> wrote:

> On 11/27/2011 07:04 AM, Avi Kivity wrote:
> > On 11/24/2011 08:03 PM, Luiz Capitulino wrote:
> >> Avi,
> >>
> >> I'm getting the following panic very early on boot on a F16 VM (latest
> >> qemu.git head 40897c9):
> >>
> >> [    0.068018] Kernel panic - not syncing: Boot APIC ID in local APIC unexpected (-1 vs 0)
> >> [    0.070006] Pid: 1, comm: swapper Not tainted 3.1.0-7.fc16.x86_64 #1
> >> [    0.071004] Call Trace:
> >> [    0.072035]  [<ffffffff814acb8e>] panic+0x91/0x1a5
> >> [    0.073027]  [<ffffffff81b831ca>] native_smp_prepare_cpus+0x24c/0x300
> >> [    0.075010]  [<ffffffff81b76c0d>] kernel_init+0x85/0x158
> >> [    0.075993]  [<ffffffff810527eb>] ? schedule_tail+0x27/0x6c
> >> [    0.076017]  [<ffffffff814be5f4>] kernel_thread_helper+0x4/0x10
> >> [    0.077022]  [<ffffffff81b76b88>] ? start_kernel+0x3b6/0x3b6
> >> [    0.078009]  [<ffffffff814be5f0>] ? gs_change+0x13/0x13
> >>
> >> After some debugging and I found out that this only happens when '-cpu host'
> >> is passed, and according to git bisect it's caused by the following commit:
> >>
> >> commit 66e3dd9282141b5ae75637c9676002cf3ceeb988
> >> Author: Avi Kivity<avi@redhat.com>
> >> Date:   Wed Nov 9 15:44:36 2011 +0200
> >>
> >>      i386: derive '-cpu host' from KVM_GET_SUPPORTED_CPUID
> >>
> >
> > Strange, since it looks like cpuid 1 (ebx) returns the correct APIC ID.
> >
> > Anthony, I think we should revert that commit and refactor cpuid for
> > 1.1.  The logic is spread over too many places which makes it hard to
> > reason about.
> 
> Ack.

Anthony, are you going to revert it yourself or do you prefer a patch?
I can provide it if needed...

> 
> Regards,
> 
> Anthony Liguori
> 
> >
>