[libvirt] [PATCH v2 1/2] conf: add xml element devices/pvpanic

[Daniel P. Berrange]

On Wed, Dec 04, 2013 at 08:39:58AM -0700, Eric Blake wrote:
> On 12/03/2013 11:31 PM, Hu Tao wrote:
> 
> >>
> >> pvpanic is a qemu term, but I could see the feasibility of other
> >> hypervisors having a paravirt device with a sole purpose of notifying
> >> the host about panics.  Do we want to come up with a more generic name?
> > 
> > Give it a generic name is easy, but what about attributes? different
> > hypervisors may have different paravirt devices with different
> > attributes, we can't just mix attributes of unrelated devices into one
> > generic device. Make the devices concrete and accept/reject it if
> > hypervisors recognize it or not is better.
> 
> Then do what we've done in the past - separate the presence of a type of
> device from the driver-specific attributes, something like:
> 
> <devices>
>   <panic>
>     <driver type='qemu' ioport='0x505'/>
>   </panic>
> ...
> 
> where we use the type='' field of <driver> to toggle between a
> discriminated union of any other per-hypervisor specific attributes.  By
> default, you don't need a <driver> subelement; requesting <panic/> is
> sufficient to use the defaults for the current hypervisor.
> 
> Dan, do you have any thoughts on the best representation to use?  Or is
> Hu's original proposal of:
> 
>   <pvpanic ioport='0x505'/>

I'm not a fan of doing a special case attribute for 'ioport' - this is
something something that should be part of an <address> element, since
ioport numbers are a generic addressing concept for many devices.
eg ISA serial / parallel ports have IRQ / IO ports IIUC.


Daniel
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