[libvirt] [PATCH 02/10] conf: support backend domain name in disk and network devices

[Daniel P. Berrange]

On Fri, Feb 06, 2015 at 09:09:56PM +0100, Marek Marczykowski-Górecki wrote:
> On Fri, Feb 06, 2015 at 08:03:43PM +0000, Daniel P. Berrange wrote:
> > On Fri, Feb 06, 2015 at 07:11:40PM +0100, Marek Marczykowski-Górecki wrote:
> > > On Fri, Feb 06, 2015 at 05:36:40PM +0000, Daniel P. Berrange wrote:
> > > > On Thu, Feb 05, 2015 at 06:17:08AM +0100, Marek Marczykowski-Górecki wrote:
> > > > > At least Xen supports backend drivers in another domain (aka "driver
> > > > > domain"). This patch introduces XML config option for such setting as
> > > > > 'domain' attribute of 'source' element. Verification its content is left
> > > > > for the driver.
> > > > > 
> > > > > In the future same option will be needed for USB devices (hostdev
> > > > > objects), but for now libxl doesn't have support for PVUSB.
> > > > > 
> > > > > Signed-off-by: Marek Marczykowski-Górecki <marmarek at invisiblethingslab.com>
> > > > > ---
> > > > > Changes in v2:
> > > > >  - describe in docs/formatdomain.html.in
> > > > >  - enforce empty domain tag (only 'name' attribute allowed)
> > > > > 
> > > > > Changes in v3:
> > > > >  - change <domain name='xx'/> element to domain='' attribute of source
> > > > >    element - this is more logical place
> > > > >  - grammar of docs
> > > > 
> > > > I hate to say this, but I think the previous way you had it was
> > > > a better approach. A <domain name='xxxx'/> element is something
> > > > we can potentially add to any type of device, whereas the
> > > > <source domain='xxx'> approach will need to have different
> > > > XML for each type of device as they don't all have a <source>
> > > > element present.
> > > 
> > > Ok, but perhaps some better name? When I read something like:
> > > <interface type='bridge'>
> > >   <ip address='1.2.3.4'/>
> > >   <domain name='netvm'/>
> > > </interface>
> > > it is really not obvious what domain this is about. When the same would
> > > be supported for PCI passthrough, it will be even more confusing:
> > > <interface type='hostdev' managed='yes'>
> > >   <driver name='vfio'/>
> > >   <source>
> > >     <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
> > >   </source>
> > >   <mac address='52:54:00:6d:90:02'/>
> > >   <domain name='netvm'/>
> > > </interface>
> > > 
> > > Any ideas for a better name?
> > 
> > Perhaps <iodomain name="netvm"> to clarify it a little ?
> 
> Hmm, if we consider multi-word names, perhaps <backenddomain
> name='netvm'>?

A little verbose, but I think that's ok, since use of this feature won't
be the common case. So this is fine with me unless someone has better
ideas.

Regards,
Daniel
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