[yocto] [meta-raspberrypi] linux kernel rt

[Andrei Gherzan]

Hi all,

On Thu, Dec 14, 2017 at 12:09 PM, Andreas Müller <schnitzeltony at gmail.com>
wrote:

> On Thu, Dec 14, 2017 at 11:40 AM, Mirza Krak <mirza.krak at gmail.com> wrote:
>
>> 2017-12-14 9:41 GMT+01:00 Andreas Müller <schnitzeltony at gmail.com>:
>> > On Thu, Dec 14, 2017 at 2:58 AM, Sherif Omran <
>> sherifomran2000 at gmail.com>
>> > wrote:
>> >>
>> >> hey guys,
>> >>
>> >> any body tried the real time kernel? I get an error, it is snot in the
>> >> compatibility list.
>> >> can we skip it?
>> >>
>> >> thanks
>> >>
>> >> --
>> >
>> > Good news: I use RT kernel only together with VC4 graphics and have
>> lots of
>> > fun on PI2/3.
>> > Bad news: As far as I know it is not in meta-raspberrypi but in my fork
>> [1].
>> > There were attempts to land the RT-patches in meta-raspberrypi but that
>> was
>> > denied for huge patch size :(
>>
>> If the patch size was the only problem one can pull it by doing the
>> following in the recipe:
>>
>> SRC_URI += " \
>>     https://cdn.kernel.org/pub/linux/kernel/projects/rt/4.9/patc
>> h-4.9.65-rt56.patch.gz;name=rt-patch
>> \
>> "
>>
>> SRC_URI[rt-patch.md5sum] = "9caa7b541d8c84c2d5c5f58985982e95"
>> SRC_URI[rt-patch.sha256sum] =
>> "47dfb518c78d8cbaafd4ab9130eb26fe0170be9189b580ab26209ef679309539"
>>
>> Note that above sums are "random" and not the for the actually file
>> but are there for reference.
>>
>> That way you do not need to keep a copy of it in meta-raspberrypi.
>>
>> --
>>
> Hi Mirza,
>
> Problem is that patches need alignments sometimes either caused by
> Raspberry-Pi-specific adjustments or versions not matching exactly - RT
> kernel patch updates are less frequent than kernel updates. Anyway: git is
> very good at maintaining huge text content and this should not be a problem
> these days. Another discussion about RT kernel was to have an extra kernel
> for it and I never understood why. To me that seems nothing but an extra
> maintenance burden.
>
> However - just wrote to Paul: I plan to be at FOSDEM and we can discuss
> there how to get back to one layer only (not mine!) making everybody happy
> :)
>
>
I remember the discussion. Indeed that was the reason and the
recommendation was to maintain a separate linux-raspberry fork where
whoever has interest in this will maintain on top of linux-raspberrypi this
patch. Obviously that didn't happen but I'd like to see it landing.

--
Andrei Gherzan
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