Re: [Qemu-devel] [PATCH] tcm_vhost: Expose ABI version via VHOST_SCSI_GET_ABI_VERSION

[Michael S. Tsirkin]

On Wed, Jul 25, 2012 at 02:10:48PM -0700, Nicholas A. Bellinger wrote:
> On Wed, 2012-07-25 at 16:10 +0300, Avi Kivity wrote:
> > On 07/24/2012 11:45 PM, Nicholas A. Bellinger wrote:
> > 
> > >> > diff --git a/drivers/vhost/tcm_vhost.h b/drivers/vhost/tcm_vhost.h
> > >> > index e942df9..3d5378f 100644
> > >> > --- a/drivers/vhost/tcm_vhost.h
> > >> > +++ b/drivers/vhost/tcm_vhost.h
> > >> > @@ -80,7 +80,17 @@ struct tcm_vhost_tport {
> > >> >  
> > >> >  #include <linux/vhost.h>
> > >> >  
> > >> > +/*
> > >> > + * Used by QEMU userspace to ensure a consistent vhost-scsi ABI.
> > >> > + *
> > >> > + * ABI Rev 0: All pre 2012 revisions used by prototype out-of-tree 
> > >> > code
> > >> > + * ABI Rev 1: 2012 version for v3.6 kernel merge candiate
> > >> > + */
> > 
> > 
> > If it's out of tree, why consider it at all?  Put a stable ABI in tree
> > and extend it in compatible ways.
> > 
> > 
> 
> This comment was supposed to convey that ABI=0 vhost-scsi userspace code
> is not supported with tcm_vhost mainline code.
> 
> But obviously that was not clear enough here.  Updating the comment to
> reflect to make this clear.
> 
> So the main question here was if it's fine to start with ABI=1, and
> require >= ABI=1 for all vhost-scsi userspace code to function with
> tcm_vhost.
> 
> The idea was to avoid confusion for the ABI=0 vhost-scsi code that's
> been floating around for the last 2 years.
> 
> --nab
> 
> 
> 
> 
> 
> 

Yes but I am guessing that code does not invoke the ABI ioctl?

-- 
MST