[yocto] Current state of linux-raspberrypi-rt?

[Trevor Woerner]

On Sun, Jun 25, 2017 at 10:32 PM, Paul D. DeRocco
<pderocco at ix.netcom.com> wrote:
> Google turns up a lot of stuff about this, but the latest I found was a
> thread from 1/5/17 that started with Trevor Woerner posting a 1MB patch,
> and that ended with him posting a message saying that it didn't actually
> work.

I posted a v1, which worked great, and continues to work great.

After posting the v1, lots of feedback was given. One of those pieces
of feedback was that I shouldn't include the entire defconfig, but
rather I should use some sort of "savedconfig" setting to generate the
full config. I had never heard of this before. I asked for more
clarification but received none. I went ahead with the v2 using this
"savedconfig" technique. It *appeared* to work (which is why I
submitted the update to the mailing list), but, after a lot of
testing, I discovered that this "savedconfig" thing didn't work. The
defconfig that was generated using this technique was useless and
nobody could provide any reason why or advice how to fix it.

So v2 didn't work, but v1 did and still does (we're using it internally).

But everyone considered v1 to not be acceptable for inclusion for a
number of reasons, so it never got merged. Besides, that work was for
a 4.4 kernel, which is now considered "old".

> Is there anything new on this? I'm trying to do some compute-intensive
> audio on an RPi3, and it really needs a real-time kernel.

Andreas Müller has a meta-raspberrypi fork in which he has an -rt
recipe for a 4.9 kernel:
https://github.com/schnitzeltony/meta-raspi-light