Ubuntu ARM and the linaro kernels

[David Rusling]

Good discussion.   Stupid question - what is the Ubuntu sauce?   I'll ask the kernel dudes in their meeting in two minutes...

Dave

On 15 Nov 2010, at 15:53, John Rigby wrote:

> 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.
>>  * John to request upload permissions for linux-linaro only and to
>>   request commit rights to ubuntu/ubuntu-$release.git for the linaro
>>   branch only
> The plan proposed at UDS was for Steve Langasek to take over the roll of
> linux-linaro upload sponsor.  He would replace Tim G in this role.  Perhaps
> we could try this for one cycle then consider the idea of me uploading
> after that.
>>  * 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
> The easiest way to include Ubuntu Sauce is to include all of it.  It rarely
> causes merge conflicts and I can't think of an instance where it has
> caused breakage for linux-linaro so I suggest we just keep including it all.
> To include a subset would require someone to decide what subset and
> that would be extra work.
>>  * 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
>> 
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>> linaro-dev at lists.linaro.org
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>> 
> 
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