Re: [libvirt] [PATCH] qemu: add support for -device pvpanic
On Wed, Nov 27, 2013 at 06:15:27AM -0700, Eric Blake wrote:
On 11/27/2013 03:39 AM, Peter Krempa wrote:
> On 11/27/13 09:41, Hu Tao wrote:
>> qemu removes the builtin pvpanic device for all qemu versions since 1.7,
>> in order to support <on_crash>, '-device pvpanic' has to be added
to
>> qemu command line.
>>
>> Signed-off-by: Hu Tao <hutao(a)cn.fujitsu.com>
>> ---
> I remember discussions saying that it's NOT a good idea to enable this
> stuff always. As a result, this device is not being added by qemu as you
> described above. Shouldn't we only add this if the user enables
> <on_crash> actions?
You are precisely right; we MUST add a new entry under <devices> in the
<domain> XML before enabling this device.
Is a entry under <devices> for pvpanic still needed? What I thought is
that it is natural to enable pvpanic when user enables <on_crash>,
he/she even has no need to know about pvpanic.
See these threads for some ideas (although recall that qemu has been
fixed in the meantime to state that any distro shipping a qemu with
pvpanic enabled by default can be considered buggy, and that libvirt can
now assume that pvpanic will not happen without an explicit '-device
pvpanic'):
https://www.redhat.com/archives/libvir-list/2013-August/msg01184.html
https://www.redhat.com/archives/libvir-list/2013-August/msg01136.html
IIRC, at the time of the thread, the pvpanic entry under <devices> is
for addressing the compatibility of qemu 1.5(has builtin pvpanic) and
qemu 1.6 and after(has no builtin pvpanic). Since now qemu removes
builtin pvpanic for all versions, I think there is no need for pvpanic
entry in xml.
--
Regards,
Hu Tao