Installing LinuxCNC 2.9 on Raspberry Pi 4B with Preempt-RT kernel

alangibson wrote:

To anyone looking for a low latency board computer that you can actually get your hands on, check out this thread.

forum.linuxcnc.org/18-computer/48113-odr...ent-for-raspberry-pi

We've managed to get sub-20 microsecond latency under realistic test conditions.

We are hoping to migrate this to the Armbian build system which I've been playing with for a while. I've missed something with the preempt_rt but with Alan's help, I think it will be pretty easy to sort out from here. That will reduce it to a one line build command.

Hi Alan,

I have been running through the instructions all is going well (after setting up docker) but when I run

debuild -uc -us

after some time compiling taskmodule.cc I get the error below , do you know what this error means and how to fix it.

I should add that I killed the process as it seemed to have crashed.  


Thanks
Nick


Compiling emc/task/taskmodule.cc
g++: fatal error: Killed signal terminated program cc1plus
compilation terminated.
make[2]: *** [Makefile:287: objects/emc/task/taskmodule.o] Error 1
make[2]: Leaving directory '/home/nick/build/src'
make[1]: *** [debian/rules:50: override_dh_auto_build-arch] Error 2
make[1]: Leaving directory '/home/nick/build'
make: *** [debian/rules:38: build] Error 2
dpkg-buildpackage: error: debian/rules build subprocess returned exit status 2
debuild: fatal error at line 1182:
dpkg-buildpackage -us -uc -ui failed

Still couldn't get debuild to complete so reverted to using build in place. this time it compiled.


Regards
Nick

Thanks for this guide.  I think I got everything installed properly but encountered a couple areas where I had questions:

1. QT Designer script asked for "Run In Place" vs "Package" installation; I assumed Package.
2. sudo dpkg -i mesact_1.1.2_arm64.deb had an error message saying it wasn't a valid Debian archive; I downloaded mesact_1.2.3_arm64.deb and installed instead.  Not sure if this will be an issue with the previous compilation steps before it.

Thanks again!

~Mor

This might muddy the waters.....
There is not really any need to be building software on the pi when a  version of Debian Bookworm exists for several versions of the pi.
Here is some instructions I put together in April/May 2022.
docs.google.com/document/d/1S0K-UBlXnsYC...b_0/edit?usp=sharing

Note the Debian images do not install a graphical environment but we can install them using tasksel
Some of the tips came from a video showing Debian Bullseye I found over 12 months ago.
I don't think there is a solution to install  qtpyvcp and probe-basic yet.

I'll look into that. I tried the standard official install instructions but after the auto-updates the pi wouldn't boot anymore so I gave up. This thread's instructions worked for me so far.

Thanks for the great tutorial. I wanted to have a kernel debian package of the realtime kernel. Unfortunately, there is no official deb package. So I decided to do it on my own. It was much more complex than expected. So I created a  GitHub repository . But be careful its work in progress.

rodw wrote:

I don't think there is a solution to install  qtpyvcp and probe-basic yet.
Hi Rod,

I've been looking around to see if someone's been able to install probe_basic on a rpi4 setup but haven't found anything. Do you know if this has been accomplished yet ?

Thanks !

Jay

P.S. I should mention we're trying to use the BTT SKR v1.4 Turbo.