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

[Jan Kiszka]

On 2011-10-08 17:16, Richard W.M. Jones wrote:
> On Fri, Oct 07, 2011 at 12:16:07PM +0200, Jan Kiszka wrote:
>> 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.
> 
> It's a lot more hairy and requires dev tools to be installed on the
> production host.
> 
> The core file is technically simple, has no dependencies, can be moved
> to another machine for analysis, and contains all the data (not just a
> backtrace).

As explained in the other replies: It is way more future-proof to use an
interface for this which was designed for it (remote gdb) instead of
artificially relaxing reasonable constraints of the migration mechanism
plus having to follow that format with the post-processing tool.

Jan

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