[yocto] RFC: User configurable recipe features

[William Mills]

On 10/13/2011 04:30 AM, Jack Mitchell wrote:
> On 12/10/2011 17:59, Darren Hart wrote:
>>
>> 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.
>>>
>>> I'm currently doing some size-related work for Sony (including
>>> some work to support 4K stacks).
>>>
>> Perhaps while I have the attention of a few interested parties, it would
>> be a good time for a poll. I'm interested in your motivation for smaller
>> images.
>>
>> Are you building SoC's with memory on die and needing to keep the memory
>> footprint down to save precious die real-estate?
>
> no
>
>>
>> Are you looking at creating mass-market products and saving a few
>> pennies on the flash storage translates to real money, so you want to
>> minimize the physical size?
>
> no
>
>>
>> Are you concerned with boot time, and have connected larger image sizes
>> with longer boot times?
>
> I am concerned with boot time, but don't believe it is image size that 
> ramps it up.
>
>>
>> Is there another motivating factor for your interest in small images?
>
> Yes, a smaller system which is easier to check, build and maintain. In 
> my office I am the leading driver for using linux in a team of 3 (two 
> software, one fpga developer) so the less time I spend building, 
> rebuilding and checking features I don't need, to ensure they don't 
> comprimise the stability of the system, the more faith they have in 
> the system I'm putting forward.
>

Ahhh, nice one Jack.

I had a similar thought this morning.  As the target system gets smaller 
the tolerance for spending X amount of time building non-target code 
goes down and the expectation of being able to use a "modest machine" 
goes up.

What is a modest machine?  Yocto quotes build times for a "refernce 
machine" that is pretty up to date and not on the low end.  To me, a 
modest machine is the laptop Mom & Dad bought "Stacy" when she graduated 
from High School and went off to College.  Stacy is now a junior and is 
exploring embedded Linux.  This might be an i3 2 GB machine.  A China 
based startup may also give its engineers modest machines.  I think many 
TI'ers would claim they have been stuck on modest machines for long periods.

So If a sato image takes 1 hour to build on the reference machine it may 
take 4 hours to build on a modest machine.  Of that time perhaps 1 hr is 
spent building host side stuff.

If your image is just kernel, busybox, and uclibc you probably only 
spend 1/2 hour building that on a modest machine.  Question is does 
oe-core/poky still make you build 1 hr worth of host stuff?

I know Richard's answer will be shared state but I want to see how that 
really works out.  This is an area we plan on playing with over the next 
release cycle.


>> Thanks,
>>
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