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

[Daniel P. Berrange]

On Thu, Dec 05, 2013 at 06:47:51PM +0800, Hu Tao wrote:
> On Thu, Dec 05, 2013 at 10:07:40AM +0000, Daniel P. Berrange wrote:
> > On Thu, Dec 05, 2013 at 10:41:13AM +0800, Hu Tao wrote:
> > > On Wed, Dec 04, 2013 at 03:53:17PM +0000, Daniel P. Berrange wrote:
> > > > On Wed, Dec 04, 2013 at 08:46:53AM -0700, Eric Blake wrote:
> > > > > On 12/04/2013 08:42 AM, Daniel P. Berrange wrote:
> > > > > >> 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.
> > > > > 
> > > > > So something more like:
> > > > > 
> > > > >   <pvpanic>
> > > > >     <address type='ioport' slot='0x505'/>
> > > > >   </pvpanic>
> > > > > 
> > > > > and introducing a new type='ioport' namespace into the <address> XML
> > > > > since it is yet another numbering system for guest-visible addressing?
> > > > 
> > > > Yes, I'm not sure I'd call the type 'ioport' - the address type reflects
> > > > the bus/controller type that the device is associated with.  What is the
> > > > "bus" type that a pvpanic device is attached to ? Is it a ISA bus device,
> > > > or is it a "platform" device or something else ? eg it might be appropriate
> > > > to use
> > > > 
> > > >   <address type='platform' ioport='0x666'/>
> > > 
> > > It's an ISA device. So the address should be:
> > > 
> > >     <address type='isa' ioport='0x505'/>
> > 
> > Ok. It looks like it does not require an IRQ line though IIUC. For the
> > general ISA address type though, we want to represent both ioport and
> > IRQ values. So I guess we need the IRQ attribute to be optional in some
> > manner.
> 
> Just to confirm it, so the general ISA address looks like:
> 
>      <address type='isa' ioport='0xaaa' irq='123'/>
> ?

Yes, looks good.

> I checked attributes of several qemu ISA devices, iobase and irq are common,
> but some device(isa-ide) has iobase2. Should we handle it as well?

I guess we can just have an optional   ioport2  attribute too if we ever
need to support that devices. i'd just ignore it for now though to keep
life simple.

Daniel
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