On 03/21/2014 05:12 AM, Laszlo Ersek wrote:
> Two additional points:
>
> On 03/20/14 21:56, Laszlo Ersek wrote:
>> On 03/20/14 21:38, Christian Borntraeger wrote:
>>> Qiao Nuohan,
>>>
>>> is there a reason why you did not implemented the HMP part for that format
>>> of kdump compressed format? After all this is a patch mostly for
>>> developers,
>>> so a HMP interface might come handy. Do you already have some patch in
>>> preparation or know somebody doing it?
>>
>> http://thread.gmane.org/gmane.comp.emulators.qemu/249283/focus=250059
>
> - HMP interface could be implemented as a fully new command of course,
>
> - the feature being targeted at developers strikes me as a completely
> unexpected idea. The main goal in my understanding is to allow the
> management layer (libvirt) to save a compressed vmcore when the guest
> panicks, crashes, or the admin feels like it. For communication with
> another program, QMP is actually preferable.
>
> So I'm certainly not against anyone adding a HMP interface too, but it
> cannot be an extension to the current HMP command (because it would
> break existing HMP command lines unless the HMP parser were reworked
> too), plus during review I saw no reason to stall the series even
> longer, for a side feature that I perceived to be of low importance (and
> I actually thought that Qiao Nuohan shared that notion).
Yes, my main purpose is let "virsh dump --memory-only" can dump a small
core that can be used to analyze kernel. So HMP is not that important to me.
On 03/21/2014 05:51 AM, Paolo Bonzini wrote:
> Il 20/03/2014 22:28, Laszlo Ersek ha scritto:
>> On 03/20/14 22:18, Christian Borntraeger wrote:
>>> On 20/03/14 21:56, Laszlo Ersek wrote:
On 03/20/14 21:38, Christian Borntraeger wrote:
> Qiao Nuohan,
>
> is there a reason why you did not implemented the HMP part for that format
> of kdump compressed format? After all this is a patch mostly for
> developers,
> so a HMP interface might come handy. Do you already have some patch in
> preparation or know somebody doing it?
http://thread.gmane.org/gmane.comp.emulators.qemu/249283/focus=250059
Laszlo
>>> So in essence: Due to the limitations of the command line parser we cannot
>>> add the format to the hmp command line.
>>> So something like adding
>>>
>>> dump_guest_memory_set_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
>
>
>
--
Regards
Qiao Nuohan
