Re: [Qemu-devel] [RFC PATCH 1/1] ceph/rbd block driver for qemu-kvm

[Anthony Liguori]

On 05/25/2010 04:14 AM, Avi Kivity wrote:
> On 05/24/2010 10:38 PM, Anthony Liguori wrote:
> > > - Building a plugin API seems a bit simpler to me, although I'm to
> > > sure if I'd get the
> > >    idea correctly:
> > >    The block layer has already some kind of api (.bdrv_file_open, 
> > > .bdrv_read). We
> > >    could simply compile the block-drivers as shared objects and 
> > > create a method
> > >    for loading the necessary modules at runtime.
> >
> > That approach would be a recipe for disaster.   We would have to 
> > introduce a new, reduced functionality block API that was supported 
> > for plugins.  Otherwise, the only way a plugin could keep up with our 
> > API changes would be if it was in tree which defeats the purpose of 
> > having plugins.
>
> We could guarantee API/ABI stability in a stable branch but not across 
> releases.

We have releases every six months.  There would be tons of block plugins 
that didn't work for random sets of releases.  That creates a lot of 
user confusion and unhappiness.

Regards,

Anthony Liguori