From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@redhat.com>
Subject: Re: VM not booting anymore after Ubuntu upgrade
Date: Wed, 04 Aug 2010 14:29:08 +0300
Message-ID: <4C594F04.5010106@redhat.com>
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To: =?ISO-8859-1?Q?Andr=E9_Weidemann?= <Andre.Weidemann@web.de>
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  On 08/04/2010 02:22 PM, Andr=E9 Weidemann wrote:
> On 04.08.2010 12:31, Avi Kivity wrote:
>> On 08/04/2010 10:38 AM, Andr=E9 Weidemann wrote:
>>>
>>>> Please enable ftrace:
>>>>
>>>> # mount -t debugfs debugfs /sys/kernel/debug
>>>> # cd /sys/kernel/debug/tracing
>>>> # echo 100000 > buffer_size_kb
>>>> # echo kvm > set_event
>>>> # echo 1 > tracing on
>>>>
>>>> run the guest and kill qemu immediately when you get to the blank=20
>>>> screen
>>>> (use SDL so you can see it immediately). Then post
>>>> /sys/kernel/debug/trace somewhere.
>>>
>>> I ran the trace and put the ouptut here:
>>> http://ilpss8.dyndns.org/~andrew/qemu-kvm.trace.gz
>>>
>>
>>
>> <...>-26008 [001] 5175193.046430: kvm_exit: reason exception rip 0xf=
c842
>> <...>-26008 [001] 5175193.046430: kvm_page_fault: address fc842
>> error_code 9
>> <...>-26008 [001] 5175193.046432: kvm_entry: vcpu 0
>> <...>-26008 [001] 5175193.046434: kvm_exit: reason cr_access rip 0xf=
c796
>> <...>-26008 [001] 5175193.046435: kvm_cr: cr_write 0 =3D 0x10
>> <...>-26008 [001] 5175193.046442: kvm_entry: vcpu 0
>> <...>-26008 [001] 5175193.046444: kvm_exit: reason exception rip 0xf=
c799
>> <...>-26008 [001] 5175193.046447: kvm_entry: vcpu 0
>> <...>-26008 [001] 5175193.046449: kvm_exit: reason exception rip 0xf=
c799
>> <...>-26008 [001] 5175193.046449: kvm_page_fault: address feffd066
>> error_code 9
>> <...>-26008 [001] 5175193.046453: kvm_inj_virq: irq 13
>>
>> #GP at fc799.
>>
>> fc78f: 0f 20 c0 mov %cr0,%eax
>> fc792: 66 83 e0 fe and $0xfffffffe,%eax
>> fc796: 0f 22 c0 mov %eax,%cr0
>> fc799: ea 9e c7 00 f0 ljmp $0xf000,$0xc79e
>>
>> I think we're in big real mode and your kernel has trouble emulating=
 the
>> ljmp. Can you try latest seabios[1]? Commit 0f788893a8bba has a=20
>> workaround.
>>
>>
>> [1] git://git.linuxtogo.org/home/kevin/seabios.git
>
> Thank you very much. Running qemu-kvm with the latest seabios fixed=20
> the problem. The VM is running fine again.
>

Still I'd like to get this fixed.  What's your host kernel version?

--=20
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.