[yocto] RFC: User configurable recipe features

[Tim Bird]

On 10/12/2011 09:59 AM, 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?

Yes. - this is the primary one for me/Sony.  We have dual-core/dual-OS cameras
where the ram budget for the Linux side of the device is only 10 meg.
We are working on medical products with flash budgets of 8 meg and ram
budgets of 4 meg.

We are currently doing a fair amount with execute in place, to conserve
RAM versus flash.

> Are you concerned with boot time, and have connected larger image sizes
> with longer boot times?
Yes.

> Is there another motivating factor for your interest in small images?
Smaller images should theoretically run faster, due to less pressure
on CPU caches.  I don't know of any meaningful measurements of this,
but it's an interesting possibility.

Also, it's nice to minimize the memory footprint to reduce power
consumption.
 -- Tim

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