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 <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
