Re: [Qemu-devel] [PATCH] Change the virtio-block storage class to PCI_CLASS_STORAGE_SCSI

[Christoph Hellwig <hch@lst.de>]

On Thu, Apr 30, 2009 at 11:18:16PM +0300, Dor Laor wrote:
> Christoph Hellwig wrote:
> >On Thu, Apr 30, 2009 at 10:13:48PM +0300, Dor Laor wrote:
> >  
> >>Windows virtio driver cannot pass DTM (certification) tests
> >>while the storage class is PCI_CLASS_STORAGE_UNKNOWN.
> >>    
> >
> >Well, it isn't scsi so this is wrong.  Tell these certification people
> >to fix their test.
> >  
> It's also not unknown... someone I know implemented scsi pass through so 
> it is
> more close to scsi than to unknown..
> These certification people are M$ so it is simpler to do this harmless 
> change instead
> of waiting some light years.

It only supports limited scsi cdb passthrough _if_ it's using a raw host
device supporting the SG_IO ioctl on Linux.  That's a lot of ifs and
whens and definitively not anything like a SCSI HBA.  Now fortunately
the pci class IDs don't matter too much in real life, but I'd rather
not change it from the correct to the wrong one.  Especially as there
might be all kinds of weird breakages in existing setups when the pci id
changes underneath on a migration / upgrade of the host.

So if you really need this to please a broken testcase add an option to
qemu to use a different pci id just for this broken certification test,
similarly to various other OS workarounds.