Re: [Qemu-devel] [PATCH] vl: allow "cont" from panicked state

[Paolo Bonzini]

Il 22/08/2013 10:38, Laszlo Ersek ha scritto:
>> > To support 1.5, libvirt should simply be ready to react to unanticipated
>> > GUEST_PANICKED events.  reboot-on-panic will simply be broken for 1.5
>> > and Linux 3.10+ guests. :(
> I'm probably misunderstanding the discussion, but it might be possible
> to disable pvpanic even in 1.5 from the host side, with the following hack:
> 
>   -global pvpanic.ioport=0
> 
> In qemu, this will either configure a working pvpanic device on ioport
> 0, or the pvpanic device will be genuinely broken. At least it doesn't
> (obviously) break other stuff (in v1.5.2):
> 
> (qemu) info mtree
> I/O
> 0000000000000000-000000000000ffff (prio 0, RW): io
>   0000000000000000-0000000000000000 (prio 0, RW): pvpanic
>   0000000000000000-0000000000000007 (prio 0, RW): dma-chan

No, you're not misunderstanding the discussion.

Depending on the priorities of the pvpanic and legacy-DMA regions, it
would break DMA channel 0.  Channel 0 is (was) used for DRAM refresh, so
it should not have any visible effect.  However, it may not be entirely
disabling pvpanic, just making it mostly invisible.

Paolo