Re: [Ksummit-discuss] [CORE TOPIC] Mainline kernel on a cellphone

[Tim Bird <tim.bird@sonymobile.com>]

On 07/23/2015 08:40 AM, Mark Brown wrote:
> On Thu, Jul 23, 2015 at 08:42:51AM -0400, Steven Rostedt wrote:
> 
>> Although is this something to be a core topic or a tech topic? Does
>> this affect all subsystems, or just a set of drivers? Note, a core
>> topic wont get as much time for discussion as a tech topic would.
> 
> It's basically all subsystems that get impacted, at the minute I'd say
> it's more a plan of action and process discussion than a technical one
> though in the context of KS planning that's quite probably the same
> thing.
> 
>> Also, what is expected to be solved at KS?
> 
> Tim Bird (Cced) has been running some sessions at other conferences
> scoping the problem and discussing ways to move forward on this, another
> similar session might be useful.

As Mark says, I've been working on almost exactly this topic for several
months now.  Last year I conducted a survey investigating obstacles
that developers (mostly corporate product developers) have in mainlining.
There are lots of non-technical issues that are worth working on (version
gap, corporate incentives, training, etc.), but which are outside
the scope of the kernel summit.

There are also some technical areas where I think coordinated
effort might be useful, to identify deficiencies and collaborate on
progress.  These might be worth discussing at the summit.

In March of this year, I analysed code from several shipping phones
(representing a number of different SoCs, including both ARM and
Intel-architecture CPUs), and found that most products have between
1.2 and 3 million lines of code out-of-tree.  We are still in progress of
finding patterns of out-of-treeness, to inform decisions about technical
projects going forward.

There is now a wiki page at:
See http://elinux.org/Kernel_areas_of_focus_for_mainlining
In particular it has a table showing certain areas that tend to have
a lot of out-of-tree code (e.g. most phones have between 80K to
100K of lines of wireless driver support out-of-mainline)

IMHO it would be useful to discuss these areas, to see if there
are technical reasons for these deficiencies, and work to resolve
them.
 -- Tim