Re: [Qemu-devel] pvpanic plans?

[Paolo Bonzini]

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Il 31/10/2013 15:32, Eric Blake ha scritto:
> On 10/31/2013 08:30 AM, Michael S. Tsirkin wrote:
>> On Thu, Oct 24, 2013 at 10:39:03AM +0800, Hu Tao wrote:
>>> Hi All,
>>> 
>>> I know it's been a long time since this thread. But qemu 1.7 is
>>> releasing, do you have any consensus on this?
>> 
>> I think the biggest issue is the new PANICKED state. Guests 
>> already have simple ways to halt the CPU, and actually do.  I 
>> think a new state was a mistake. So how about the following?
>> Does it break anything? (Untested).
> 
> Don't you still need to halt the guest on a panic event, for 
> management to have a chance to choose what to do about the panic? 
> I'm suspecting this patch does break things.

Yes, it does.  But I think that, once we make the pvpanic device is
optional, to a large extent there is no bug.  Adding the pvpanic
device to the VM will make libvirt obey <oncrash> instead of the
in-guest setting, and that's it.

Two months have passed and no casualties have been reported due to
pvpanic.  Let's just remove the auto-pvpanic from all machine types in
1.7 (yes, that's backwards incompatible in a strict sense), document
it in the release notes, and hope that the old QEMU versions with
mandatory pvpanic die of old age.

All the advantages/disadvantages from my original messages still
apply.  Let's ignore the disadvantages and just KISS.

Paolo
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