From: Dave Anderson <anderson(a)redhat.com>
Subject: Re: [Crash-utility] crash cannot work for the newest qemu's core
Date: Thu, 28 Jun 2012 16:38:56 -0400
----- Original Message -----
> At 06/22/2012 09:06 PM, Dave Anderson Wrote:
> >
> >
> > ----- Original Message -----
> >>
> >>
> >> ----- Original Message -----
> >>> Hi, all
> >>>
> >>> When I use crash to deal with the vmcore generated by 'vrish
dump',
> >>> I meet the following error:
> >>>
> >>> crash: seek error: kernel virtual address: ffffffff8180f1e0 type:
"cpu_possible_mask".
> >>>
> >>> When I specify '-d 8' to get more information, I found the
following message:
> >>>
> >>> NOTE: KVM/QEMU CPU_SAVE_VERSION 12 is greater than supported version 9
> >>>
> >>> So I guess crash does not support it now. Does anyone have plan to fix
it?
> >>>
> >>> Thanks
> >>> Wen Congyang
> >>
> >> Hi Wen,
> >>
> >> Also, because of your familiarity with this area, I certainly invite you
> >> to take a look at this... ;-)
> >>
> >> Thanks,
> >> Dave
> >
> > Hi Wen,
> >
> > On a related note, what is the status with your "virsh
dump-guest-memory"
> > replacement of "virsh dump"? The last I saw, it seemed like the qemu
guys
> > finally seemed willing to accept it?
>
> dump-guest-memory is not a virsh's sub command. It is a qemu monitor command.
> The patches for qemu and libvirt have been merged into newest qemu/libvirt.
OK, but now I'm confused...
I was presuming that you could run the new "dump-guest-memory" command from
the KVM host, specifying a particular guest, and it will create an ELF vmcore
that the crash utility can read. But I don't know what the term "qemu monitor
command" means? Is it a command that can be executed from a shell command line?
And will "virsh dump" still exist? And if so, why?
Dave
This is a patch set in libvirt side:
https://www.redhat.com/archives/libvir-list/2012-June/msg00404.html
In summary:
- dump-guest-memory is a qemu monitor command, the protocol of which
is explained in
http://wiki.qemu.org/QMP.
- To get ELF-formatted vmcore, we specify --memory-only option to
virsh dump command, then virsh dump uses dump-guest-memory monitor
command vir QMP protocol, instead of migrate monitor command.
- Note that the default behaviour remains calling migrate command.
BTW, we can call monitor commands using virsh qemu-monitor-command but
they are restricted, according to this FAQ:
-
http://wiki.libvirt.org/page/FAQ#Can_I_connect_to_the_QEMU_monitor_with_l...
Also, this is helpful to know how virsh commands use qemu monitor
commands:
-
http://wiki.libvirt.org/page/QEMUSwitchToLibvirt#Monitor_command_equivalence
Thanks.
HATAYAMA, Daisuke