Re: Libvirt NVME support

> On Mon, Nov 23, 2020 at 09:47:23 +0000, Thanos Makatos wrote: > > > On Thu, Nov 19, 2020 at 10:17:56 +0000, Thanos Makatos wrote: > > > > > As a starting point a trivial way to model this in the XML will be: > > > > > > > > > > <controller type='nvme' index='1' model='nvme'> > > > > > > > > > > And then add the storage into it as: > > > > > > > > > > <disk type='file' device='disk'> > > > > > <source dev='/Host/QEMUGuest1.qcow2'/> > > > > > <target dev='sda' bus='nvme'/> > > > > > > > > 'target dev' is how the device appears in the guest, right? It should be > > > > something like 'nvme0n1'. I'm not sure though this is something that > we > > > can > > > > put here anyway, I think the guest driver can number controllers > arbitrarily. > > > > > > Well, it was supposed to be like that but really is not. Even with other > > > buses the kernel can name the device arbitrarily, so it doesn't really > > > matter. > > > > > > > Maybe we should specify something like BDF? Or is this something > QEMU > > > will > > > > have to figure out how to do? > > > > > > > > > <address type='drive' controller='1' bus='0' target='0' unit='0'/> > > > > > </disk> > > > > > > > > > > <disk type='file' device='disk'> > > > > > <source dev='/Host/QEMUGuest2.qcow2'/> > > > > > <target dev='sdb' bus='nvme'/> > > > > > <address type='drive' controller='1' bus='0' target='0' unit='1'/> > > > > > </disk> > > > > Revistiting your initial suggestion, it should be something like this > > (s/sdb/nvme0): > > > > <disk type='file' device='disk'> > > <source dev='/Host/QEMUGuest2.qcow2'/> > > <target dev='nvme0' bus='nvme'/> > > <address type='drive' controller='1' bus='0' target='0' unit='1'/> > > </disk> > > Note that the parser for 'dev' is a bit quirky, old, and used in many > places besides the qemu driver. It's also used with numbers in non-qemu > cases. Extending that to parse numbers for nvme but not for sda might > become ugly very quickly. Sticking with a letter at the end ('nvmea' > might be a more straightforward approach. Then I think we should just stick with 'nvme'.

> That certainly is correct if you include the "type='nvme'" attribute. Great, so the following would be a good place for us to start? <controller type='nvme' index='1' model='nvme'> <disk type='file' device='disk'> <source dev='/Host/QEMUGuest2.qcow1'/> <target dev='nvme' bus='nvme'/> <address type='nvme' controller='1' ns='1'/> </disk> <disk type='file' device='disk'> <source dev='/Host/QEMUGuest2.qcow2'/> <target dev='nvme' bus='nvme'/> <address type='nvme' controller='1' ns='2'/> </disk>