Re: [libvirt] [PATCH 0/2 v3 use qemu's dump-guest-meory when vm uses host device
At 04/19/2012 04:38 PM, Daniel P. Berrange Wrote:
On Thu, Apr 19, 2012 at 09:03:16AM +0800, Wen Congyang wrote:
> Currently, we use migrate to dump guest's memory. There is one
> restriction in migrate command: the device's status should be
> stored in qemu because the device's status should be passed to
> target machine.
>
> If we passthrough a host device to guest, the device's status
> is stored in the real device. So migrate command will fail.
>
> We usually use dump when guest is panicked. So there is no need
> to store device's status in the vmcore.
>
> qemu will have a new monitor command dump-guest-memory to dump
> guest memory, but it doesn't support async now(it will support
> later when the common async API is implemented).
>
> So I use dump-guest-memory only when the guest uses host device
> in this patchset.
Hmm, doesn't the new command generate dump files in a totally
different format to the existing command ? If so I don't
think it is nice behaviour to silently switch between 2 different
dump formats depending on the XML config. I think we'd want some
kind of flag to specify what format is desired.
Agree with it. But the new command is not a async command, and it
will block the other operation. So I only use it when the vm uses
host device(migrate command will fail in this case).
The new command will be converted to async command later(after
async API is implemented). I think we can allow the user specify
the format when the new command is async command.
Thanks
Wen Congyang
Daniel