run Linuxcnc on xenomai with EVL(the realtime core)

rodw
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19 Apr 2024 21:11 #298669 by rodw

Replied by rodw on topic run Linuxcnc on xenomai with EVL(the realtime core)

I''ve forgotton where, but there is code that decides whether to build for rtapi or realtime.
There is a conditional that decides which type of thread to create for the servo thread. I think rtapi is decided by an environment variable.
My take was this needed to be changed to acommodate EVL and this code would need reviewing.
github.com/LinuxCNC/linuxcnc/tree/master/src/rtapi

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andypugh
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20 Apr 2024 19:10 #298747 by andypugh

Replied by andypugh on topic run Linuxcnc on xenomai with EVL(the realtime core)

It should be possible to run the linuxcnc-uspace debian package with Xenomai if you install the xenomai-uspace helper package.

Unfortunately I have not figured out how to build that package on demand, but it did get built until 2.8.4 on Jessie, Precise and Wheezy. You can find it here, for example:
www.linuxcnc.org/dists/wheezy/2.8-rtpreempt/binary-amd64/

Supoport for building these helper packages was probably removed in this commit: github.com/LinuxCNC/linuxcnc/commit/6f28...5d5904ffec3998a833ef
Which I would quite like to reverse, but that is not a trivial task this much further down the line.

It is still possible to build from source for RTAI (I do it all the time) and it might still work with Xenomai. Have you tried

./configure --with-realtime=path-to-xenomai

?

It might work, there is ertainly mention of Xenomai in the configure script:
github.com/LinuxCNC/linuxcnc/blob/db906d...rc/configure.ac#L143

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cgy
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21 Apr 2024 06:37 #298761 by cgy

Replied by cgy on topic run Linuxcnc on xenomai with EVL(the realtime core)

Thank you all for the suggestions. Unfortunately, using Xenomai 4's EVL with LinuxCNC didn't work for me; I've tried everything.
Following my instructor's advice, I switched to using Xenomai 3 for the build. （this is a topic I'm exploring）During the build process, Xenomai was successfully detected.

However, when running it, the real-time core of Xenomai still wasn't utilized.

I found some posts on the forum from a few years ago with the same issue,

forum.linuxcnc.org/9-installing-linuxcnc...ith-xenomai3?start=0

but I couldn't find a solution. Do any of you have new suggestions?

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andypugh
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21 Apr 2024 10:29 #298770 by andypugh

Replied by andypugh on topic run Linuxcnc on xenomai with EVL(the realtime core)

I would like to understand this myself.

Is there any evidence of the uspace_xenomai.cc file being compiled?

Maybe you could try installing the uspace 2.8.4 deb + matching uspace-xenomai deb on your Xenomai3 system and see what happens?

This is where the rtapi wrapper app prints "POSIX non-realtime" or "POSIX realtime" and it is still looking for Xenomai: github.com/LinuxCNC/linuxcnc/blob/master...ce_rtapi_app.cc#L797

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run Linuxcnc on xenomai with EVL(the realtime core)

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