Ubuntu ARM and the linaro kernels

[Loïc Minier]

 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
 * John to request upload permissions for linux-linaro only and to
   request commit rights to ubuntu/ubuntu-$release.git for the linaro
   branch only
 * if someone cares about limiting the Ubuntu Sauce which goes into the
   linux-linaro Ubuntu package which goes into Linaro images, then that
   someone ought to start discussion on splitting and limiting the Sauce
   which goes into the linaro branch with the Ubuntu Kernel Team; I
   don't think this fundamentally holds up anything though
 * if someone cares about providing better vanilla Linaro Kernel builds,
   e.g. .debs, then that someone ought to start some spec on providing +
   testing these builds -- I'm happy to help here  :-)



   Cheers,
-- 
Loïc Minier