Re: Uses of Linux backports in the industry

[Richard Weinberger <richard@nod.at>]

Am 24.06.2015 um 11:55 schrieb Enrico Weigelt, metux IT consult:
> Am 24.06.2015 um 11:19 schrieb Richard Weinberger:
> 
> Hi,
> 
>> Porting PREEMPT_RT is not that easy.
>> Did you ever?
> 
> I know.
> 
> OTOH, is backporting drivers to ancient kernels (where internal APIs
> often are _completely_ different) really easier ? Perhaps it might look
> so, if it's just one individual driver - but often it doesn't keep this
> way, sooner or later other things pop up.

At the end of the day customers will do what is less costly.
Sometimes backporting a driver is much less effort.
That's why we have the excellent backports project.

>> So, you rewrite all drivers and the board support from scratch?
> 
> Sometimes, if I have to. Because - on my own experience - what SoC
> vendors provide usually is pretty unusable, just a quick showcase.
> 
> Right now, I'm working on a project w/ some imx53-based board.
> What freescale provides here is practically unusable. Really ancient
> (last time I checked, it was an old 2.6.x), unsable and insecure
> (anybody had a closer look at their "kgsl" patch or their gst-plugin ?)
> 
> We'll have to drop the whole idea of using the GPUs, due to lack of
> support - the existing driver/libgl is known to be broken and insecure,
> no support from fsl whatsoever, we're lacking resources for a full
> reverse engineering, and moving to another SoC is out of question
> (at least for the forseeable future). So, it ends up in having no
> GPU, therefore no GL/GSL, therefore no QtQuick/QML.
> 
> 
> Pavel already mentioned the correct way to go: chip vendors should
> provide proper (mainline'able) patches, or at least full specs.

Sure, in a perfect world. But as of now we have to deal with that.

Thanks,
//richard
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