Ubuntu ARM and the linaro kernels

[Oliver Grawert]

hi,
Am Montag, den 15.11.2010, 08:53 -0700 schrieb John Rigby:
> On Mon, Nov 15, 2010 at 4:28 AM, Loïc Minier <loic.minier at ubuntu.com> wrote:
> >  Folks, I think this thread is circling a bit back to itself, perhaps
> >  summarizing where we stand and what problems we're trying to solve
> >  would help?
> >
> >
> >  * Linaro integrates its kernel tree into Ubuntu for two reasons:
> >   - because Linaro uses Ubuntu as a base to build its own derived
> >     images (out of Ubuntu)
> >   - because Linaro wants its kernel shipped/available in distributions
> >     such as Ubuntu/MeeGo/whatever for mutual benefit of the distro and
> >     of Linaro.  For instance, Ubuntu users could install this kernel
> >     instead of the official Ubuntu one, or Ubuntu could build images
> >     from this kernel (as proposed in the original email).
> >
> >  * there are currently the following *three* trees for the Ubuntu Linaro
> >   kernel packages to happen (for maverick):
> >   - git://git.linaro.org/kernel/linux-linaro-2.6.35.git -- upstreamish
> >     tree maintained by Nicolas, based on upstream git tree with patches
> >     relevant to Linaro merged in; the Linaro Kernel
> >   - git://git.linaro.org/ubuntu/linux-linaro.git -- Ubuntu-ish tree
> >     for the linux-linaro source package in Ubuntu or in Linaro PPAs
> >     maintained by jcrigby, based on the Linaro Kernel tree with
> >     packaging and the Ubuntu stuff ("Sauce") merged in
> >   - git://kernel.ubuntu.com/ubuntu/ubuntu-maverick.git linaro branch --
> >     pretty much the same as jcrigby's tree maintained by the Ubuntu
> >     kernel team; it's mostly a copy of jcrigby's tree when it gets
> >     uploaded to Ubuntu, unless the Ubuntu kernel team has to do any
> >     minor adjustments/fixups before upload; it exists only because
> >     jcrigby can't upload and because /ubuntu is restricted to the
> >     official Ubuntu Kernel Team
> >
> >  So what problems / questions are we trying to solve?
> >  * security support: Linaro isn't in the business of long-term security
> >   support of its trees, however I understand that it wouldn't be a big
> >   problem to simply add the *Ubuntu* linux-linaro package and the
> >   kernel.ubuntu.com git tree to the list of packages/trees which get
> >   security updates from the Ubuntu Security Team, especially if the
> >   Ubuntu ARM Team moves to this package/tree as their base for some
> >   images
> >  * for Linaro, the Ubuntu Sauce stuff doesn't add any much value and is
> >   a distraction (causes more merge efforts, might cause extra bugs
> >   etc.)
> >
> >
> >  Is this a fair summary?  Did I miss anything?
> >
> >
> >  I am not sure I understand the point of contention with the Ubuntu
> >  Sauce stuff; is it causing problems to Linaro right now?
> >   Linaro GCC is released in source form and then integrated in the
> >  Ubuntu gcc-4.x packages which have tons of patches added on top; this
> >  is not ideal for Linaro Toolchain WG, but it's part of the process to
> >  check whether bugs do apply to the pristine Linaro source, just like
> >  you need to test a pristine upstream GCC or Linux when reporting bugs
> >  upstream.
> >
> >  There are definitely things we could do to improve the Ubuntu Sauce:
> >  * split this stuff more; e.g.:
> >   - packaging goes in one tree (I think this is already split out?)
> >   - patches which come from upstream or were acked upstream go into
> >     another tree
> >   - patches which are Ubuntu specific such as AUFS go into one or
> >     multiple separate trees
> >  * we could review the current sauce stuff and only merge in features
> >   which are really needed for Linaro images and Ubuntu ARM images; aufs
> >   doesn't seem to be needed anymore for instance?  Maybe this makes
> >   things more complex for little gain though
> >  * we could stop merging patches from upstream from Ubuntu, and have
> >   them flow in via Linaro instead; again, maybe this makes things more
> >   complex for little gain
> >
> >
> >  My opinion is that the current approach is okay modulo two things:
> >  - we should drop one of the two packaging trees; the
> >   linaro / jcrigby versus kernel.ubuntu.com split is useless
> >  - we could provide pristine kernel builds, built from the Linaro Kernel
> >   directly and without any Ubuntu Sauce
> >   . in fact these exist already, they just aren't tested and they use a
> >     random config: http://hudson.dooz.org/
> >   . if we want Linaro Kernel .debs instead of standalone zImage/uImage,
> >     we could do something like
> >     https://wiki.ubuntu.com/Kernel/MainlineBuilds
> >
> >
> >  Proposed plan
> >  * Oliver/Ricardo to confirm with Ubuntu Security Team whether it's ok
> >   to base Ubuntu ARM images on linux-linaro tree as constructed
> >   currently
> I can't speak for the Ubuntu ARM folks but I believe their main concern was if
> I stopped including Ubuntu Sauce.
right, that was one of my concerns, another was how much the kernels
differ from BSP source we usually use for ubuntu images so that all
on-board devices work out of the box.

then there is the question about ubuntu configs (which you answered) 
(since we try to keep our QA efforts low we expect the same or a close
to same config to the ubuntu kernel in the arm kernels (i.e. a user
needs to be able to plug in his DVB-T USB stick and get the same results
in ubuntu arm as he gets on his ubuntu laptop))

my main concern though is the 18 month support timeframe which we
provide for ubuntu images.

i think from the linaro side i got sufficient answers now, it seems we
could use johns trees as a base for ubuntu images but would have to have
someone from the ubuntu kernel team and the ubuntu security team for
maintaining security and config alignment. 

the situation in the kernel team wrt arm maintenance is just being
sorted afaik, so i expect to get some info in this thread in the not to
far future ...

ciao
	oli
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