Ubuntu ARM and the linaro kernels

[Nicolas Pitre]

On Tue, 9 Nov 2010, Oliver Grawert wrote:

> hi,
> Am Montag, den 08.11.2010, 15:46 +0000 schrieb Jamie Bennett:
> > > * linaro kernels used in ubuntu ARM would need to move to the  
> > > supported
> > > package set (main) which makes them fall under all freeze restrictions
> > > the kernel team sets for ubuntu (only SRUs post kernel freeze, patches
> > > and changes all need to go through the ubuntu-kernel mailing list etc)
> > 
> > I think we can deal with the via the SRU process. We have already been
> > using the SRU process this cycle for kernel changes so its a non-issue.
> well, the kernel freeze and SRU process would happen for you guys a lot
> earlier due to that, thats why i wanted to bring it up ...

While I see lots of goodness in trying to reduce this duplicated effort, 
I think there is still a slight disconnect between Linaro's and Ubuntu's 
goals for their respective kernels.  While Ubuntu should focus on the 
greatest support to enhance the user experience, Linaro is there to 
promote support of the ARM architecture in general through consolidation 
towards the mainline kernel.

This means that, for example, that the Linaro kernel will not merge 
anything with no hope of ever being accepted upstream, including stuff 
like a single patch adding 45 thousand lines of code in one shot to 
support proprietary 3D graphics libraries.  Now that we have a corporate 
backed entity to promote upstream contributions for the greater benefit 
of all members, we should not weaken this principle by carrying 
proprietary drivers with a dead future which would send a wrong signal.

However, the Ubuntu kernel has little choice but to merge those 
proprietary drivers as the unfortunate fact is that there is simply no 
alternative (yet) to produce a viable 3D user experience.  And I'm 
afraid that this burden has to be carried on the Ubuntu side.  Let's 
hope that the reduced engineering effort on the Ubuntu side due to the 
work now undertaken by the Linaro team will compensate for this 
continuing burden.

Linaro is also driving a work force which should serve the greater ARM 
Linux ecosystem, including Ubuntu on ARM of course, but other entities 
as well.  Therefore the Linaro process cannot always be tied to the 
Ubuntu process.  This means that Linaro may not always follow the exact 
same schedule as Ubuntu, and things like Ubuntu sauce patches and/or 
kernel configs might not make sense in all Linaro contexts.

> one option i see is that we use the linaro branches as base and add all
> distro kernel specifics on top here, but thats something the kernel team
> has to agree to since they will have to be the ones doing that work (and
> i personally cant really judge how much work this is for them).

I'm afraid this might have to be the case.  However, Git is pretty 
powerful and effective to carry such a task.  Of course, for anything 
that should move towards mainline, it is best if Linaro carries such 
patches directly instead of Ubuntu.


Nicolas