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

[Wen Congyang <wency@cn.fujitsu.com>]

At 10/10/2011 03:01 PM, Jan Kiszka Write:
> On 2011-10-10 08:59, Wen Congyang wrote:
>> At 10/10/2011 02:52 PM, Jan Kiszka Write:
>>> On 2011-10-10 04:21, Wen Congyang wrote:
>>>> At 10/09/2011 06:23 PM, Richard W.M. Jones Write:
>>>>> On Sun, Oct 09, 2011 at 10:49:57AM +0200, Jan Kiszka wrote:
>>>>>> 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.
>>>>>
>>>>> Any interface that isn't "get this information off my production
>>>>> server *now*" so that I can get the server restarted, and send it to
>>>>> an expert to analyse -- is a poor interface, whether it was designed
>>>>> like that or not.  Perhaps we don't have the right interface at all,
>>>>> but remote gdb is not it.
>>>>
>>>> What about the following idea?
>>>>
>>>> Introduce a new monitor command named dump, and this command accepts a filename.
>>>> We can use almost all migration's code. We use this command to dump guest's
>>>> memory, so there is no need to check whether the guest has a unmigratable device.
>>>
>>> I do not want to reject this proposal categorically, but I would like to
>>> see the gdb path fail /wrt essential requirements first. So far I don't
>>> see it would.
>>
>> ‘gdb path fail /wrt essential requirements’
>>
>> what does it mean?
> 
> That you explain why reading reading memory and processor states via the
> remote gdb interface and dumping it into a proper core file cannot be
> made working for you.

First, I think crash can not analyze such core file. But it is not very important.

What is remote gdb interface? Do you mean that: the supporter uses gdb from another machine
to connect to customer's machine and get the data? If so, this way can not be
used when the customer needs to dump the guest's memory automatically when watchdog timeouts.

Thanks
Wen Congyang

> 
> Jan
>