Kernel ABI breakage

[Ben Collins]

On Wed, 2008-02-20 at 07:47 -0700, Tim Gardner wrote:
> Fabio M. Di Nitto wrote:
> > Hi guys,
> > 
> > I spoke to Tim on IRC a few days back about problems introduced by some 
> > recent updates in LUM and he suggested to take it to a wider audiance.
> > 
> > I filed a bug to keep track of the issue: #192559
> > 
> > but is the general approach of upgrading entire subsystems in LUM (or any 
> > other package for the matter) that needs to be reviewed.
> > 
> > So far i don't recall this problem happening before, but now it's clear 
> > out of a default install.
> > 
> > Fabio
> > 
> > PS CC me on reply. I am not subbed to this mailing list.
> > 
> > --
> > I'm going to make him an offer he can't refuse.
> > 
> 
> After some experimentation I think can propose at least one short term
> solution.
> 
> 1) Disable CONFIG_SOUND in the kernel.
> 
> 2) Commit duplicated (and modified) headers from LUM ALSA into the
> kernel tree. Remove LUM versions of the duplicate headers to enforce
> correct compilation.

If you are going to take the time to update headers in the kernel to
match lum, then you might as well drop the entire alsa update in the
kernel to make it more coherent. As discussed yesterday on the team
call, this still doesn't resolve the case where we need to update alsa
in lbm post-release. It also makes the alsa in the kernel tree totally
bogus, and will cause lots of confusion.

> 3) Port CONFIG_SND/CONFIG_ALSA dependent drivers from the kernel to LUM
> (cx88 and saa7134).
> 
> Assuming the LUM ALSA header modifications do not cause compilation
> errors, this will at least allow external subsystems to compile against
> the kernel and generate the correct ABI.
> 
> While this solution works for ALSA, its not particularly elegant. If we
> take on more duplicate subsystems like this in LUM, then we'll have to
> design something better.
> 
> rtg
> -- 
> Tim Gardner tim.gardner at ubuntu.com
> 
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>