[ubuntu-x] Proprietary driver ABI handling

[Bryce Harrington]

On Mon, Jan 31, 2011 at 09:40:58AM +1100, Christopher James Halse Rogers wrote:
> Hey all
> 
> As a part of the drive to Xserver 1.10, I've noticed that the fglrx and
> nvidia proprietary drivers don't have the appropriate Depends: to
> prevent the X server being updated from underneath them. (nvidia bug: LP
> #616214, no existing fglrx bug)
> 
> A simple fix would be to add ${xviddriver:Depends} to their dependency
> fields, which will add a dependency on the current Xserver video ABI
> metapackage.  This is sub-optimal in two ways:
> 1) We need to do a mock “rebuild” against each new Xserver ABI
> 2) It makes checking Xserver bugs against older ABIs unnecessarily
> difficult.
> 
> Since the proprietary drivers support multiple server ABIs, I suggest
> that we keep a list of these in the packaging and add a dependency
> satisfied by any of the appropriate xserver-xorg-video ABIs.
> 
> This has the advantage that the default “forgot to update” failure mode
> is that an upgrade fails with unresolved dependencies rather than a
> broken X, and less work at Xserver upgrade time.
> 
> It has the disadvantage that we need to maintain a list of supported
> ABIs, and we need to produce the dependency field outside of the xsfbs
> helper system, so they could get out of sync.  I don't think these are
> big disadvantages, as the supported ABI list changes approximately once
> per cycle, and the xsfbs system changes even less often (and we'd need
> to deliberately update when it does anyway).

(The kernel also tends to break the proprietary drivers.  Would be nice
to have a solution for that as well.)

I think it's an idea worth trying, but might be wisest to leave 'til
after alpha-2 as I think it'll need a bit more testing than we have time
to coordinate at the moment.

Bryce