On 04/19/2012 02:45 AM, Wen Congyang wrote:
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.
You missed the point. We need 2 flags - one now that says whether to dump via migrate-to-file or via dumping memory (I'd name it VIR_DOMAIN_CORE_DUMP_MEMORY_ONLY), and another flag later to state whether to block the dump or whether to do the dump asynchronously (similar to the recent block-job-cancel conversion, I'd name it VIR_DOMAIN_CORE_DUMP_ASYNC). In other words, the user should be able to choose which format they get, for 3 of the 4 combinations of user's XML vs. available qemu commands: hostdev no hostdev flag = 0 error migrate-to-file flag = MEMORY_ONLY dump-guest-memory dump-guest-memory and the choice of async or blocking is orthogonal to the above choice. -- Eric Blake eblake@redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org