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Searched around regarding isolcpus and force turbo mode, found this thread: forum.linuxcnc.org/9-installing-linuxcnc...th-preempt-rt-kernel

Used this:
echo -n 'isolcpus=1,2,3 idle=poll processor.max_cstate=1' | sudo tee -a /boot/cmdline.txt
echo -n 'performance' | sudo tee /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
and
echo -n 'force_turbo=1' | sudo tee -a /boot/config.txt
Not sure if that's correct but it seems to show up in the right files.
Restarted the pi after this.

Unfortunately this seems to have made the problem worse.
As soon as I start linuxCNC I now get "error queueing read".
 

You may have lost some latency reducing setup when you upgraded

On the RPI4 I think isolcpus 2,3 and force turbo mode are usually required

Back at it. Was trying to use G71 but seems it didn't exist in the version I had installed.
This pushed me to install "linuxcnc-2.9.1-bookworm-rpi4.img.xz" from linuxcnc.org/docs/html/getting-started/getting-linuxcnc.html.
After having a bunch of issues(seems menu-config didn't correctly set locale) I managed to get it semi-working.

New problem is I'm getting "hm2/hm2_7i96.0: error finishing write!" which seems to make the mesa card throw an error and stop working.
This happens within a minute of starting LinuxCNC but also happens if I test the axis in PnCConf.
Only change here is that I've upgraded to 2.9.1, previously it worked fine even after an hour. So I suspect it's software related.

I've been searching the forum and found some threads but I'm not understanding things.
-From what I gather this could be due to latency spikes in the network communication?
-A possible 'fix' is to change what kernel I'm using, but how do I change kernel?
-Another thing I've seen mentioned is to increase servo period but does not seem to fix the issue?

Any help is much appreciated as I'm yet again stuck so close to the finish line.
 

Hello everyone! I am relatively new to linuxCNC, as well as linux overall and am having trouble installing the 2.9.1 bookworm image (found on the linux cnc downloads page) onto my  Raspberry Pi 4 (8 gig version). The current problem is that after the install it asks for a user name and password to login. I have tried to use the Raspberry pi imager to set the password prior to install with no success. How should I move forward? Is there a previous release that may work? Is there another method to get LinuxCNC on my PI? 

Checked that the governor is set to performance.

But yeah if it is overheating it will throttle down. A heatsink\fan might help.

But if the NUC is ok I'd stick with that.

Thanks for the info and the time you put in making the PI image. I must just have a bum pi4, I get the sculls error at boot but it boots up and runs. I downloaded the image you have linked to this thread and loaded my config after setting the network interface to 10.10.10.1 and leaving wifi off, I ran it for a bit and I got realtime servo thread errors and then the joint following errors, same config runs on my I5 Intel NUC. I wonder if my pi is is overheating or has some other hardware issue. I need to find another pi4 and try again. Thanks!

It may take a while tho, hopefully not too long.

One thing of note, in raspi-config there's an option to switch between wayland & X11 backends, Under "Advanced Options" -> "A6". Without this option some of the interfaces wont run because of the references to X11 functions.

I've got xfce running on mine and it does seem a bit "snappier" but that could be "all in my mind".

One thing I really like is how easy it is to boot from USB. Tho I'm just using a flash drive ATM as I have a NVME hat on the way, which should be interesting.

The image I built was copied to linuxcnc repos so no.
The later one of mine has some changes around repositories and also added network manager because guys were complaining bout not being able to easilly set the wifi settings (which can be set in menu-config anyway)

2.8 used a 32 bit kernel, this is 64 bit
All of the isolcpus settings are already done for you.
Lots of guys are using this with 1 ms servo period without following errors.
Following errors are related to your tuning, error finishing read is a hardware issue which is a kernel problem affecting mesa cards but we have not seen reports of that on the pi. 

 

I wanted to add another data point for the community.  This is....
() orangepi 5 plus (not using hdmi, but rather remote with 'ssh -X'.  I've not see that make much difference from being on the head)
() kernel: github.com/Joshua-Riek/linux.git branch v6.6-rk3588-hdmi with patch-6.6-rt15.patch
() linuxcnc from raspberrypi iso
() cmdline: idle=poll isolcpus=4,5
() latency-histogram --sbinsize 400 --show (with 10 glxgear and misc other commands being run)
() rtapi_app:T#[01] assigned to cpus 4 and 5, respectively (manual reassignment of threads for testing) 
     >> ps -T -eo pid,tid,class,rtprio,ni,pri,psr,pcpu,stat,wchan:14,comm | grep rtapi

        1614    1614 TS       -   0  19   6  8.4 SLsl -              rtapi_app
        1614    1615 TS       -   0  19   7  0.1 SLsl -              rtapi_app:mesg
        1614    1616 FF      98   - 138   4  8.1 SLsl -              rtapi_app:T#0
        1614    1617 FF      97   - 137   5  0.2 SLsl -              rtapi_app:T#1
     >> sudo taskset -cp 4 1616
     >> sudo taskset -cp 5 1617
cpus 4-7 appear to be the faster A76 cores; there seems to be a noticeable speed improvement over cores 0-3. 
 

Is this a different image than the one on the downloads ,link below? I am unable to get one linked below to work with my mesa 7i76e, I keep getting  following errors even with the servo thread set to 2ms. I had the same config working under 2.8 on the same pi 4b. I remember having to set the system to stay on one core to get it working, is that still needed?

-Thanks


www.linuxcnc.org/iso/linuxcnc-2.9.1-bookworm-rpi4.img.xz

I've send Mesa an email about this.... for what it's worth.. That's the only thing I can do about it I guess...

A friend of my wanted to swap my Pi4 1GB to his 4GB version. Very happy with that!! For now I can go further with Linuxcnc 2.9.1.

They are talking about 2-3 times faster, but it feels like 4-5 times faster, booting, browsing, etc... Only running Linuxcnc is endless slower...

About power draw of the Pi5, when Linuxcnc will work on it, I wil just set the usb_max_current_enable in config.txt. 7c80, SSD and Pi5 together only use 10Watt in normal state.

sorry i not has longtime can go to looking forum because my table computer(raspberrypi4) has broken and all has need do new image and build all my bookmarks new can go to internet and looking forum. new bookworm image not run good my raspian, lag lot.
you say change path ??? under (RS274NG)
user and subroutine, what i need change ???
i has try run test g-code "linuxcnc" text. but if i move manual bit top off wood corner, and then bush "touch off/antasten" button and bush Z current. and then run example text g-code, machine run code but far top off wood, on to air. not in to wood carving thats text.
i has try antasten many other current,G54,G92,gxx what here have but alltime i run g-code bit go to up far and run on air this g-code, not to wood piece.
i not understand now how i can (zero) all and make position have zero bit hight on top off wood corner and run g-code to in wood not far out up air.
ok, i try copy this you zip file to my machine and try new all again.

That can be setup by placing a file in /etc/sudoers.d
With Linuxcnc's raspberry pi Bookworm installer, this was the default behaviour and we removed the feature. (by deleting the user's file)

I think this link explains how to do it. But what would I know I only undid it!
forums.bunsenlabs.org/viewtopic.php?id=5503

This was our script to remove the file created by the default installer. 
rm -f /p2/etc/sudoers.d/010_${USERNAME}-nopasswd

A 2nd hand PC that is able to run Linuxcnc with a Mesa card is cheaper than a Raspberry Pi, at least in most cases.

Tommy is the guru on second hand PCs for Linuxcnc, generally laptops are a no go, in case you were wondering.

thankfully (kinda?) my machine is big enough that the space required by a tower PC is not worth factoring in. The electrical cabinet is bigger than many wardrobes
and it even has a nice swing out shelf for the computer :-D

The size is only kinda of benefit because i dont know when I'll ever machine anything that size, and I dont know where im going to park the lawn mower :-D