Re: [PATCH RESEND] tools/libxl: add support for emulated NVMe drives

[Paul Durrant <Paul.Durrant@citrix.com>]

> -----Original Message-----
> From: Ian Jackson [mailto:ian.jackson@eu.citrix.com]
> Sent: 22 March 2017 15:02
> To: Paul Durrant <Paul.Durrant@citrix.com>
> Cc: xen-devel@lists.xenproject.org; Wei Liu <wei.liu2@citrix.com>
> Subject: RE: [PATCH RESEND] tools/libxl: add support for emulated NVMe
> drives
> 
> Paul Durrant writes ("RE: [PATCH RESEND] tools/libxl: add support for
> emulated NVMe drives"):
> > [Ian:]
> > > If and when qemu supports multiple namespaces, how will this be
> > > specified ?
> >
> > I'd guess a vdev of the form nvmeXnY would follow convention.
> 
> Right.  Sorry, I was unclear.  I meant here:
> 
>  +    1 << 28 | disk << 8                  nvme, all disks, whole disk only
> 
> Maybe we should leave some room in this bit pattern.  If we do that
> then guests only need to be told about this once, even if we support
> nvme0n2 or whatever later, and also we don't need to use more
> numbering space.
> 
> 
> Oh, wait, I have just noticed that you have reused an entry in this
> table!
> 
>        1 << 28 | disk << 8 | partition   xvd, disks or partitions 16 onwards
> ...
> > +    1 << 28 | disk << 8               nvme, all disks, whole disk only
> 
> (I didn't spot this before because the patch didn't contain the first
> of those two lines as context.)
> 

Yes, that was intentional. No need for a new concrete encoding if we ignore namespaces, as I said in the commit comment. If you want to support namespaces then it would need something new... which doesn't seem worth it since QEMU has no support.

  Paul

> 
> Ian.

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