Re: [Qemu-devel] [RFC PATCH v1 1/1] vGPU core driver : to provide common interface for vGPU.

[Neo Jia]

On Wed, Feb 17, 2016 at 02:08:18PM +0100, Gerd Hoffmann wrote:
>   Hi,
> 
> > For example, how to locate the path of a given VM?
> 
> You go ask libvirt, the domain xml will have the info.
> 
> > Whoever is going to configure
> > the qemu has to walk through *all* the current vgpu path to locate the UUID 
> > to
> > match the QEMU's VM UUID.
> 
> No.  qemu simply uses the path it get passed from libvirt.  libvirt
> simply uses whatever is stored in the domain xml.
> 
> i.e. you'll have a config like this:
> 
> <domain type='kvm'> 
>   <name>rhel7-vfio</name>
>   <uuid>0990b05d-4fbd-49bf-88e4-e87974c64fba</uuid>
>   [ ... ]
>   <devices>
>     [ ... ]
>     <hostdev mode='subsystem' type='pci' managed='yes'>
>       <source>
>         <address sysfs='/sys/devices/virtual/vgpu/${name}'/>
>       </source>
>       <address type='pci' domain='0x0000'
>                bus='0x00' slot='0x04' function='0x0'/>
>     </hostdev>
> 
> > I think I has answered this, UUID is not a user space or kernel space
> > concept, it is just a generic way to represent object,
> 
> Yes.  But the above sounds like you want to use UUIDs to *link* two
> objects, by assigning the same uuid to both vm and vgpu.  This is *not*
> how uuids should be used.  Each object should have its own uuid.
> 
> You can use uuids to name the vgpus if you want of course.  But the vgpu
> uuid will will have no relationship whatsoever to the vm uuid then.
> 

Agree. I should made it clear that it should be a separate object.

Thanks,
Neo

> cheers,
>   Gerd
>