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Date: Fri, 07 Oct 2011 14:56:56 +0200
From: Jan Kiszka <jan.kiszka@siemens.com>
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Subject: Re: [Qemu-devel] [Question] dump memory when host pci device is
 used by guest
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To: Wen Congyang <wencongyang@gmail.com>
Cc: qemu-devel <qemu-devel@nongnu.org>, Luiz Capitulino <lcapitulino@redhat.com>

On 2011-10-07 14:25, Wen Congyang wrote:
> =E4=BA=8E 2011/10/7 18:16, Jan Kiszka =E5=86=99=E9=81=93:
>> On 2011-10-07 11:46, Wen Congyang wrote:
>>> Currently, virsh dump uses monitor command migrate to dump guest's me=
mory
>>> to file, and we can use crash to analyze the file.
>>>
>>> Unfortunately, virsh dump can not work if guest uses host pci device.=
 The
>>> reason is that the device's status is also needed to migrate to remot=
e machine,
>>> and the host pci device's status is not stored in qemu. So it is unmi=
gratable.
>>>
>>> I think we can  we can add a option to qmp command migrate(eg: skip) =
to allow
>>> the user to skip the check, and this option should be used only when =
dumping
>>> the guest's memory.
>>
>> Why not simply attach gdb? That works independently of migration.
>=20
> If qemu has some problem, we can use gdb to debug it. But if guest os=20
> has problem
> (eg:kernel panic and kdump does not work), we should dump guest's memor=
y=20
> and use
> crash to analyze.

qemu-system-xxx -s (or "gdbserver" via monitor if qemu is already
running), gdb vmlinux, then "target remote :1234".

Jan

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