Xen/OpenVZ out-of-tree module builds and ABI

[Ola Lundqvist]

Hi Ian

On Mon, Oct 11, 2010 at 09:10:59AM +0100, Ian Campbell wrote:
> On Sun, 2010-10-10 at 19:34 +0100, Ben Hutchings wrote:
> > On Sun, 2010-10-10 at 09:51 -0700, Russ Allbery wrote:
> > > Hello, kernel folks.
> > > 
> > > We (the NVIDIA packaging team) noticed a commit from the latest Debian
> > > kernel packaging that said:
> > > 
> > >      Refresh ABI reference files
> > > 
> > >      Remove files for OpenVZ and Xen featuresets, where we are not
> > >      trying to keep the module ABI stable.
> > > 
> > > (r16351) and weren't entirely sure what that meant.
> > > 
> > > We maintain module builds for the NVIDIA kernel drivers (which are
> > > non-free) using a build package that builds versions for the current
> > > kernel, primarily for stable releases.  Currently, we're building modules
> > > for Xen and OpenVZ kernels as well as the regular kernels.
> > > 
> > > Does this change mean that the module builds for Xen and OpenVZ kernels
> > > may not continue working with later versions of those kernels because the
> > > ABI might not be stable?
> > 
> > Correct.  We try hard to avoid ABI breakage after a freeze and in stable
> > updates and we have so far succeeded with the 'standard' images, but we
> > have given up on a stable ABI for the OpenVZ and Xen featuresets.
> 
> I can't speak for OpenVZ but I think we are unlikely to pull in a
> complete new drop of the Xen pvops patch now that we are frozen (Bastian
> -- what do you think?) so in theory we can maintain the ABI we have
> today for future uploads. That would still mean that there had been
> multiple different things calling themselves ABI 5 in Squeeze during
> development but at least it would have one meaning in the actually
> released version of Squeeze.

I'm not in full control over openvz patch but I do have some insight and that
is that it is unlikely that we will pull in many changes here as well.
Kir may have other opinion but the openvz patch seems fairly stable. I do not
think we will see any ABI breaking at this point.

Especially as we are now in deep freeze.

Best regards,

// Ola 

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