[yocto] RFC: User configurable recipe features

[Tim Bird]

On 10/12/2011 08:55 AM, Darren Hart wrote:
> meta-tiny is my experimental layer where I'm looking at what we can
> build with our existing sources and infrastructure. I've found that we
> can cut the image size to about 10% of core-image-minimal without
> changes to source code, but dropping a lot of functionality. We can get
> to something like 20% while still maintaining ipv4 networking.

This sounds cool.

> This "recipe features" thread stems from this work. Before I can
> integrate something like this into Yocto, it needs a more suitable user
> exposed configuration mechanism.
> 
> I'm working from a public git repository, but it isn't in sync with my
> local development branch as things are changing by the minute still. I
> will be pushing this to a Yocto hosted git repository in time for ELCE,
> but it will still be development/experimental. If you are interested in
> seeing what is there now, you can have a look to get an idea of what I'm
> doing. Please note this tree WILL rebase, it WILL fail to build, it WILL
> destroy your tmp dir, your sstate, and waste your time as you try and
> pick through the various options to get something that builds and boots
> ;-) Also, this repo will disappear in the next few days, but if you just
> want to see it, it's here:
> 
> http://git.infradead.org/users/dvhart/meta-tiny.git
> 
>>
>> I'm currently doing some size-related work for Sony (including
>> some work to support 4K stacks).
> 
> I'd like to have a look - is there anything out there I can read through?
Not at the moment.  I've been meaning to send my patch
for 4K stack support for ARM to linux-ARM, but haven't had
the time.  I'll see if I can push it out this week (but it
might collide with the 3.2 merge window, and I wouldn't
expect it to go straight in without it dwelling in someone's
-next tree for a bit.)

In our cameras, this saves about 300K of kernel memory.

I have no problem sending that to you if you'd like.  Just let
me know.  If mainline doesn't take it straight-away for some reason,
I'll probably hand it off to the linux-tiny project, which is back
in full swing.

> Post ELCE, I'd like to look at more source level changes we can make. In
> particular I'd like to see the >200k bzImage increase for ipv4 come
> down. In addition to that, I'm hoping to take a closer look at dynamic
> memory usage in the Linux kernel for small systems.

I have some patches for monitoring slab allocations that are helpful
for this (also something I should have already mainlined, but didn't
get to... ;-(

 -- Tim

=============================
Tim Bird
Architecture Group Chair, CE Workgroup of the Linux Foundation
Senior Staff Engineer, Sony Network Entertainment
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