Re: [Qemu-devel] [Question] dump memory when host pci device is used by guest

[Wen Congyang <wencongyang@gmail.com>]

于 2011/10/7 20:56, Jan Kiszka 写道:
> On 2011-10-07 14:25, Wen Congyang wrote:
>> 于 2011/10/7 18:16, Jan Kiszka 写道:
>>> On 2011-10-07 11:46, Wen Congyang wrote:
>>>> Currently, virsh dump uses monitor command migrate to dump guest's memory
>>>> 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 remote machine,
>>>> and the host pci device's status is not stored in qemu. So it is unmigratable.
>>>>
>>>> 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.
>>
>> If qemu has some problem, we can use gdb to debug it. But if guest os
>> has problem
>> (eg:kernel panic and kdump does not work), we should dump guest's memory
>> and use
>> crash to analyze.
>
> qemu-system-xxx -s (or "gdbserver" via monitor if qemu is already
> running), gdb vmlinux, then "target remote :1234".

Hmm, if i use qemu, i can do it as the above. But i can not hope our 
customer
do it because it is difficult for them to debug kernel.
So the customer can use 'virsh dump'(the guest is managed by libvirt) or 
autodump(if
the guest has a watchdog) to dump the memory. The supporter can debug 
kernel in another
machine.

I still think that supporting to dump memory when guest uses host pci 
device is necessay.

Thanks
Wen Congyang
>
> Jan
>