Re: [libvirt] [Qemu-devel] pvpanic plans?
On 22 August 2013 21:09, Anthony Liguori <anthony(a)codemonkey.ws> wrote:
Paolo Bonzini <pbonzini(a)redhat.com> writes:
> Not just that. Panic notifiers are called in a substantially unknown
> environment, with locks taken or interrupts already set up.
If you make the panic notify a config space write, then on virtio-pci,
it's an outb to a fixed offset within a io address that after boot is
static.
So the address could be stored in a global and accessed without a lock.
Fine for virtio-mmio too, obviously. I have a vague recollection that
config space writes on virtio-s390 are weird though. (would also
be an issue if we wanted to implement the virtio-console "emergency
write" functionality.)
-- PMM