[Qemu-devel] Re: [PATCH 0/2] fix virtio_blk serial pci config breakage

[Rusty Russell]

On Wed, 30 Sep 2009 03:01:12 am Anthony Liguori wrote:
> Rusty Russell wrote:
> > On Tue, 29 Sep 2009 11:25:20 pm Anthony Liguori wrote:
> >   
> >> 2) Passing an ATA identity page is goofy.  We should just pass the 
> >> serial number and let Linux generate the identity page.  Just because 
> >> Linux requires this as it's user space interface, that doesn't mean that 
> >> other guests will (like Windows).  Instead of exposing an opaque blob, 
> >> we should expose the information we need in a structured way.
> >>     
> >
> > I think John did this on my prompting, because it already existed as a
> > defined ABI.  If someone is going to make stuff up, isn't it better that
> > kvm does it (some of those fields might have useful values?) than linux?
> 
> We should expose Linux ABI quirks in the virtio ABI.  Down the road, 
> someone may decide that there's a better way to expose things like S/N 
> down to userspace and then in our drivers we would have to parse the ATA 
> identity page in order to figure out the S/N to expose that properly 
> through the new interface.  Moreover, there's probably an OS out there 
> that we already have to do that for.
> 
> That's a pretty ugly thing to have to do.

Calling the ATA IDENTIFY command a Linux ABI quirk is disingenuous.

Not sure what the SCSI equiv is to get a serial number (VPD?) But if everyone
is happy with 20 bytes, and John wants to do SN that way, I'll take the patch.

Still, I got to learn fun stuff about the block layer!
Rusty.