[yocto] RFC: User configurable recipe features

[Khem Raj]

On 10/12/2011 8:55 AM, Darren Hart wrote:
> Hi Tim,
>
> On 10/11/2011 04:49 PM, Tim Bird wrote:
>> On 10/10/2011 11:41 AM, Darren Hart wrote:
>>> As part of working on meta-tiny, I've come across a need (want?) to
>>> present users with the ability to select some set of features in a local
>>> configuration file that will impact the build of the image and a set of
>>> recipes.
>>
>> Can you tell me more about meta-tiny?  this is the first I've heard
>> about this (sorry if discussion went by on the mailing list and I
>> missed it), and I'm very interested.
>
>
> Tim,
>
> I'll be presenting things in more detail at ELCE, Friday @ 3:45 PM in
> the Kepler room. The summary is that I have received a lot of questions
> along the lines of "How small of an image can I build with Yocto?".

I guess yocto needs to define another profile(distro) to really 
demonstrate how small it can get. There are other distros based on 
oe-core e.g. micro and even slugos where the image sizes are really 
small slugos/uclibc image is around 2.7M eglibc based image is 3.5M


> core-image-minimal does a decent job at a small general purpose image,
> but it still has a lot of baggage that a truly size conscious developer
> doesn't need for a custom BSP.
>
> 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 "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.

this has a downside. I still favour that distro/machine should be one to 
dictate the features which should control recipe feature enable/disable 
behavior.

>
> 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?
>
> 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.
>
> Thanks,
>