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

[Jan Kiszka]

On 2011-10-18 10:31, Wen Congyang wrote:
> At 10/18/2011 04:26 PM, Jan Kiszka Write:
>> On 2011-10-18 10:25, Wen Congyang wrote:
>>> At 10/18/2011 04:19 PM, Jan Kiszka Write:
>>>> On 2011-10-18 09:58, Wen Congyang wrote:
>>>>> At 10/18/2011 03:52 PM, Jan Kiszka Write:
>>>>>> On 2011-10-18 09:15, Wen Congyang wrote:
>>>>>>> Hi, Jan Kiszka
>>>>>>>
>>>>>>> At 10/10/2011 05:34 PM, Jan Kiszka Write:
>>>>>>>> On 2011-10-10 11:02, Daniel P. Berrange wrote:
>>>>>>>>> On Mon, Oct 10, 2011 at 08:52:08AM +0200, Jan Kiszka wrote:
>>>>>>>
>>>>>>>>
>>>>>>>> Run gdb with "set debug remote 1" and watch the communication, it is 
>>>>>>>> not
>>>>>>>> that complex. But a dump command is probably simpler for those
>>>>>>>> scenarios, I agree.
>>>>>>>
>>>>>>> I have implemented the command dump and reuse migration's code. But I 
>>>>>>> meet a problem
>>>>>>> when I test it.
>>>>>>
>>>>>> Using migration code for dump is most probably the wrong approach as you
>>>>>> saw through that conflict. All you need are the register states and the
>>>>>> RAM. Reuse gdbstub services for this.
>>>>>
>>>>> Hmm, if the migration code can not be reused, I think we should define a 
>>>>> new
>>>>> qemu's vmcore format, and add some codes into crash to support such 
>>>>> format.
>>>>
>>>> Please try to avoid defining something new. Unless there is a striking
>>>> reason, standard gdb core files should be generated so that you can load
>>>> the dump directly into gdb for analysis.
>>>
>>> I am not sure whehter the standard gdb core files can not be analyzed by 
>>> crash.
>>> If not, I think we should define something new because it's easier to use
>>> crash than gdb to analyze the core files.
>>
>> gdb allows you to walk up the frame and print variables (globals &
>> local) etc.
> 
> Crash uses gdb to provide common function, and you can also use all the gdb 
> commands
> in crash.

That what's the added value here when I can use gdb directly?

Jan

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