RPI4 Raspbian 64 bit & LinuxCNC

tjmarch wrote: The problem is when you invoke Linuxcnc or latency-test form the command line. It says it is running Posix non real-time.

This can happen if you have compiled run-in-place but have not run the linuxcnc-dev/scripts/rip-environment script to set up the command-line session.

Thank you Andy for the information. But I have a question if LCNC was installed with Deb files do you have to invoke rip environment? Because I installed LCNC with Debs, not a rip environment install.

tjmarch wrote: Thank you Andy for the information. But I have a question if LCNC was installed with Deb files do you have to invoke rip environment? Because I installed LCNC with Debs, not a rip environment install.

No,

But, where did you get the LinuxCNC .debs from?

The LinuxCNC .debs need to match the real-time kernel. If you are installing 32-bit LinuxCNC debs from www.linuxcnc.org then you probably need to use the 32-bit preempt-rt kernel.

If you built your own debs, then you (usually) need to be running the RT kernel when you build the debs, and to have run "./debian/configure -r " prior to building the debs to set up the correct real-time hooks.

elovalvo wrote: Install a fresh Raspbian 64 bit from this
Raspberry Pi OS (64 bit)

elovalvo:

Do you mind if I edit your first post to point out that this is the hard way to do things if you _only_ want to run LinuxCNC on the Pi, and that there exists an easier way, ie writing the "official" LinuxCNC SD card image to an SD card?

Andypugh wrote:
But, where did you get the LinuxCNC .debs from?

I used the debs from this post where I made them on the rt kernel referred to in the post so they are 64bit and built on rt kernel.
My deb files

But did not run:
"./debian/configure -r " prior to building the debs to set up the correct real-time hooks.

I used:
cd debian
"./configure uspace"

Thank you for the reply

I followed directions to a tee and used the provided Deb files in this thread and realtime works, still have issue with latency and using pi camera but that was expected, sorry for the confusion. Thanks for the help AndyPugh

To continue experimenting with using LinuxCNC with a 64-bit kernel on Raspberry Pi 4 I prepared two SD images.

The first, downloadable at the following link:
Linux 5.4.61-rt37-v8 - LinuxCNC 2.8.1
is based on Linux raspberrypi 5.4.61-rt37-v8 with PREEMPT_RT and LinuxCNC 2.8.1

The second, downloadable at the following link:
Linux 5.10.25-rt35-v8 - LinuxCNC 2.9.0~pre0
is based on Linux raspberrypi 5.10.25-rt35-v8 with PREEMPT_RT and LinuxCNC 2.9.0~pre0

Both can be installed with:
Raspberry Pi Imager
that in the latest version (1.6.1) allows you to modify some startup parameters by using hidden commands that can be accessed with the CTRL+SHIFT+X key combination

I checked operation on Raspberry Pi 4 with 2GB and 4GB.
I don't have a Raspberry Pi 4 with 8GB, so it would be interesting to check how it works.

I can try it on the Pi400. (if I remember)

Would you expect it to work on the Pi3?

How did you make the images? How do these compare with the "official" images for latency?

I make the "official" images. I would be more than happy to pass that task on.

Ill test it on the 8gb today/tomorrow, the 32 bit version for 5.4 works very well. bonus with the 5.10, i need that for a separate project.

How do these compare with the "official" images for latency?

They were pretty much the same,like underwhelmingly the same. pretty much the same as the previous 4.19.70something 4gb ram. I thought maybe between all the images i had saved, older or newers would be faster, but with vanilla settings they are all pretty close to the same. I tested elovalvo's 32bit 5.4 kernel and the 3gb 4.19 kernel official image side by side with 4gb and 8gb units. The only real difference I noticed was the ram, but i didnt dive to deep into the kernel config or anything. I have it loaded on my test unit and it preforms as expected aside for some reason I can only ever use 25% cpu usage, like when using make -j4. I forgot about that until just now.

andypugh wrote: I can try it on the Pi400. (if I remember)

In this case, you must verify that a hal_pi_gpio module works because the Pi400 (6) version is not included in the source code.

andypugh wrote: Would you expect it to work on the Pi3?

I don't think so, because I compiled the patch for the runtime with the bcm2711_defconfig option.
Following the link lemariva.com/blog/2019/09/raspberry-pi-4...19y-performance-test
you should use the option bcm2709_defconfig

andypugh wrote: How did you make the images?

I followed the steps in the first post of this thread.
In this case, however, I took into account the suggestion to disable virtualization (KVM)
github.com/kdoren/linux/issues/5

andypugh wrote: How do these compare with the "official" images for latency?

I have not installed the official releases at this time.
These days I try to make them

andypugh wrote: I make the "official" images. I would be more than happy to pass that task on.

Just tell me which version you need and I'll be happy to prepare it