Re: [Qemu-devel] hmp interface for kdump compressed format

[qiaonuohan <qiaonuohan@cn.fujitsu.com>]

Hello guys,

I have sent the patch, please check here:

http://lists.nongnu.org/archive/html/qemu-devel/2014-04/msg00018.html

On 03/27/2014 04:38 PM, Markus Armbruster wrote:
> "qiaonuohan@cn.fujitsu.com"<qiaonuohan@cn.fujitsu.com>  writes:
>
>> On 03/27/2014 01:04 AM, Markus Armbruster wrote:
>>>>>>> So something like adding
>>>>>>>>>>>
>>>>>>>>>>>   dump_guest_memory_set_format<format>
>>>>>>>>>>>
>>>>>>>>>>>   would be the only possible solution with the hmp code as
>>>>>>>>>>> is. Correct?
>>>>>>>>>
>>>>>>>>>   Yes, one possibility would be to make the dump command stateful (=
>>>>>>>>>   compression format), and to add a new command
>>>>>>>>> setting/getting that state.
>>>>>>>>>
>>>>>>>>>   Another option would be to leave the current command intact,
>>>>>>>>> and add an
>>>>>>>>>   independent command that wouldn't take "begin", "end", nor
>>>>>>>>> "paging", but
>>>>>>>>>   would take compression format.
>>>>>>>
>>>>>>>   Another possibility is to kill begin/length from the
>>>>>>>   dump-guest-memory command.
>>>>>>>   HMP is not stable, so if that's useful we can do it.
>>>>>
>>>>>   AFAIK, kdump-compressed format can only be analyzed by crash-utility right
>>>>>   now. ELF is big but we still need it, then begin/length will help us save
>>>>>   time and space when only part of the memory is need.
>>>>>
>>>>>   IMHO, a new HMP command will be a good choice and it is more simple than
>>>>>   making dump format 'stateful'. I am not so clear about HMP, but I think
>>>>>   the new HMP command can be 'dump-guest-memory-with-format', and still
>>>>>   base on qmp_dump_guest_memory. If you guys like it, I will send a patch
>>>>>   that add this command.
>>> Paolo encouraged you to*break*  the existing HMP command instead of
>>> adding a new one.  I'd like to second that.
>>> .
>>>
>>
>> Hello markus,
>>
>> I have finish my patch as I stated in my last mail, but something is
>> wrong with my mail server, I have to wait a couple of days before
>> sending the patch. You said you prefer *breaking* the existing HMP
>> command. Since paging/begin/length is still usefull, would you please
>> give some reason and I will consider that.
>
> I'm encouraging you to design a HMP command that gives you all you need.
> Then call that dump-guest-memory, backward compatibility be damned.
>
> Would
>
>      dump-guest-memory [-p] filename [[format] begin length]
>
> do?
>
> An alternative could be two commands:
>
>      dump-guest-memory filename [format [begin length]]
>      dump-guest-memory-elf [-p] filename [begin length]
>
> This bakes the restriction "paging, begin and length work only with
> format 'elf'" into the interface.  Not sure that's a good idea, but I'm
> leaving that to folks who actually know something about this dumping
> business.
>
> If you can find better command names, go right ahead.  You could pick
> names that avoid incompatible change.  I care about avoiding
> incompatible change to exotic HMP commands even less (a lot less, in
> fact) than about naming of exotic HMP commands.
>
> .
>


-- 
Regards
Qiao Nuohan