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unknown wrote:

I've tried looking for a RT_PREEMPT kernel in the repos, but could only find kernels that were configured for Real time not Preemptive real time (which is what Linuxcnc requires).

the packages are on archive.raspberrypi.org . you want linux-image-6.12.34+rpt-rpi-v8-rt, it works for both RPi 4 and 5. there's a meta package linux-image-rpi-v8-rt that depends on the latest version of the RT kernel, but it gives you auto-updates with apt, which is not necessarily a good idea (e.g. the currently-latest 6.12.47 is hanging my Pi5 sometimes).

it is a proper PREEMPT_RT kernel:

in order for bootloader to use it, you need to add kernel=kernel8_rt.img to /boot/firmware/config.txt.

the kernel configs themselves are here .

Normally you would home the machine and then touch off on the workpiece origin. the buttons are there to do this but you can do it in gcode with G54
Maybe with your machine you always machine a full sheet but you still need to set the part origin. 

Sorry, I have no idea about the Pi... but I did get the 4b working years ago.

probe basic is not part of the linuxCNC project. You could look at qtdragon which is well documented and is part of the project. But as Tommy said, get a working system that uses axis first.

What am i missing? Seeing you all jump through so much hoops makes me wonder what are you using as a starting point?
Back when i tested Debian BookWorm 12.2 and 12.5, i downloaded the Live ISO with XFCE, remastered it and tested, it worked and did not have raspi issues. Did the same things with 12.2 Mate edition, also no raspi issues.
Granted i used the LinuxCNC version that was on Debian repos, but still, this should not matter.
Sorry, but i feel really bad seeing you go through all the trouble.
Is there something i can help with?
P.S.
Rob, sorry, i did download your ISO but did not get to testing it.

Well I tried again with a fresh LCNC install and I got almost all the way through the Probe Basic install.

Got this error on the last installation command: sudo dpkg -i python3-probe-basic_0.6.0-118.dev_amd64.deb

I looked for the application and found it but not a debian version.
Surely something is wrong with the instructions if I'm having this many issues. 
 

andypugh wrote:

unknown wrote:

Building on a system running Debian Trixie raspi-firmware IS NOT installed. (built twice on 2 different machines)
Building on a system running Debian Bookworm raspi-firmware IS installed. (single build only attempted)
This is because they fixed it (it's actually fixed in Debian 12.1) 

bugs.debian.org/cgi-bin/bugreport.cgi?bug=1065640

They fixed the Debian release files it never pushed their changes to the Debian builder until Trixie. Very annoying.

Here is an installation tutorial for Debian Trixie fresh off the press today


But yes, the 1500 pages of documentation is my go to guide...

Hiya Rod

From memory the Debian Rpi kernels lacked support for overlays, which was a show stopper for SPI.

ATM I'm cross compiling a kernel from the 6.12.y branch, I think that was what was used in the January build.

f355 wrote:

SPI works fine, it is in fact what I'm using - my little pet project is here, it is basically a rewritten Remora for a particular off-the-shelf machine. The servo latency is alright too.

I'm not insisting my approach is better for everybody, I just found it easier for myself to write a few shell scripts (install.sh and linuxcnc/pi_init/ in the repo) that set up things on the stock RPi OS image. The official linuxcnc image might have ssh enabled, but the wifi is not, or at least I couldn't find a way to configure it with my SSID quickly, and connecting Ethernet is about as much hassle as connecting a display

please read the notes on the downloads page to install wifi SSID. It is included but in the interest of latency, a network manager is not included.

Debian includes a RT kernel for the Pi 4b and it is possible to get a working RT linuxcnc install using the Debian images. But the RT kernel was not installed as a dependency from linuxcnc-uspace and needed installing separately with something like sudo apt install linux-image-rt-$uname -r) (might not have that correct. The only catch is that the images only install a text terminal with a root user. You needed to add a user, add sudo rights and then install xfce to get a working system ut it is quite doable. Sadly it does not appear support continued to the pi5.

For the Pi5 users:
www.linuxcnc.org/temp/linuxcnc-uspace_2.9.7pre_arm64.deb

@f355

I've tried looking for a RT_PREEMPT kernel in the repos, but could only find kernels that were configured for Real time not Preemptive real time (which is what Linuxcnc requires).
Debian doesn't have any support for the RPi5 as it doesn't have enough upstream kernel support.
wiki.debian.org/RaspberryPiImages#Overview

and

raspi.debian.net/tested-images/

So to get a full RT_PREEMPT kernel the only solution it would seem is to roll our own. Which would not be a suitable solution for upgrading.

One solution maybe if Linuxcnc could host suitable kernels, but I really don't see the sense in a regular upgrade regarding the kernel in this situation. I'm still running the original kernel that was built whilst building the image in Jan 2025.

BTW running pi-gen builds a couple of flavours of images everything from lite to a fully image. Tho it does use a significant amount of disk space.

I am using the Trixie version of live-build, and building on Trixie.
(I basically did a search-replace for "bookworm" in linuxcnc-live-build and swapped to Trixie. though manually and checking surrounding code.)

So I am puzzled where the splash has gone to..

Was replying to you on the laptop but didn't have the ISO there so had to swap machines. Well creakily walk upstairs, I swear I've skipped old age and just gone straight to decrepitude......enough banter.

I guess this is what your are referring to. I would say it appears as it should. Mind I haven't had a chance to test on real hardware yet.


Basically I started with a fresh fork from your repo and made the changes I thought would be required. 
Me repo and branch can be seen here, I've tried to comment the changes made within the files and within the commits as well. I think I've even mentioned using the live-build version as well.
github.com/ozzyrob/linuxcnc-live-build/tree/ozzyrob-trixie-test

Whilst I was building on my Bookworm machine I did build a live-build package & install using this the below linked codebase, installing the Trixie package on Bookworm didn't give successful results:
If using a Trixie machine to build everything should be ok. I also found using the same source and building a package for Mint 22.1 gave a successful ISO. I think I may have mentioned this before.
salsa.debian.org/live-team/live-build/-/...rixie?ref_type=heads
Which is the code base for the live-build package for Trixie.

I hope this helps.
Cheers Rob