[libvirt] [PATCH v2 2/3] xml: nodedev: add class info for pci capability

[Daniel P. Berrangé]

On Wed, Mar 20, 2019 at 12:35:14PM +0100, Pavel Hrdina wrote:
> On Tue, Mar 12, 2019 at 02:14:40PM +0300, Nikolay Shirokovskiy wrote:
> > This info can be useful to filter devices visible
> > to mgmt clients so that they won't see devices that
> > unsafe/not meaningful to pass thru.
> > 
> > Provide class info the way it is provided by udev or
> > kernel that is as single 6-digit hexadecimal.
> > 
> > Class element is not optional. I guess this should not
> > break users that use virNodeDeviceCreateXML because
> > they probably specify only scsi_host capability on
> > input and then node device driver gets other capabilities
> > from udev after device appeared.
> 
> This patch broke virt-manager testing suit [1].  It uses test driver
> a lot with custom XMLs providing required information to initialize
> test driver and one of the information is list of nodedev devices.
> 
> One can use it like this:
> 
>     virsh --connect test:///path/to/host/definition
> 
> And it will parse XML providing host definition which this patch breaks.
> 
> Yes, we can possibly fix all the test cases in virt-manager but I would
> rather make this element optional as it is not required.

Hmm, yes, I forgot that the test driver accepts /all/ the XML schemas
as inputs, even if we don't otherwise support it via the normal APIs.

I think the XML stability guarantee is not clearly defined wrt to the
test driver, and indeed I think we're reasonable in breaking compat
in this area...if we have to... but in this case I think we can be
more graceful & avoid the break without causing ourselves trouble.


Regards,
Daniel
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