[Solved] Trying to install RTAI, got errors

I have fresh install of latest Debian 12 (on quite old Intel Atom MB). I was following the docs, linuxcnc.org/docs/2.9/html/getting-start...#cha:Installing-RTAI in particular, but got errors, LinuxCNC install failed.

First, got this warning during execution of the install script:

W: Skipping acquire of configured file '2.9-rt/source/Sources' as repository 'www.linuxcnc.org bookworm InRelease' does not seem to provide it (sources.list entry misspelt?)

It got me worried, but I still performed the next step (sudo apt-get install linuxcnc). Got the following output.

Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following packages were automatically installed and are no longer required:
  libgpiod2 libwpe-1.0-1 libwpebackend-fdo-1.0-1
Use 'sudo apt autoremove' to remove them.
Suggested packages:
  mesaflash onboard
The following packages will be REMOVED:
  linuxcnc-uspace
The following NEW packages will be installed:
  linuxcnc
0 upgraded, 1 newly installed, 1 to remove and 0 not upgraded.
Need to get 25.5 MB of archives.
After this operation, 676 kB disk space will be freed.
Do you want to continue? [Y/n] y
Get:1 www.linuxcnc.org bookworm/2.9-rt amd64 linuxcnc amd64 1:2.9.2 [25.5 MB]
Fetched 25.5 MB in 5s (4,640 kB/s)   
(Reading database ... 281951 files and directories currently installed.)
Removing linuxcnc-uspace (1:2.9.2) ...
Selecting previously unselected package linuxcnc.
(Reading database ... 276444 files and directories currently installed.)
Preparing to unpack .../linuxcnc_1%3a2.9.2_amd64.deb ...
Unpacking linuxcnc (1:2.9.2) ...
dpkg: error processing archive /var/cache/apt/archives/linuxcnc_1%3a2.9.2_amd64.deb (--unpack):
 trying to overwrite '/usr/share/applications/linuxcnc-documentation.desktop', which is also in package linuxcnc-doc-en 1:2.9.2
Errors were encountered while processing:
 /var/cache/apt/archives/linuxcnc_1%3a2.9.2_amd64.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)


I understand that I've got two problems: linuxcnc not installed and RTAI kernel is not too (uname -v gives 1 SMP PREEMPT_RT Debian 6.1.90-1 (2024-05-03)).


Please, help me figure it out.

First of all I’d sort out the message from apt.
Second removing the doc package prior to installing linuxcnc with fix up the desktop message.
Thirdly the repo for the rtai kernel needs to be added.
When I get a chance, I’ll find my notes and see how I did it. Tho I think I installed the kernel and modules manually after downloading them.

This post has a link to the packages.
forum.linuxcnc.org/38-general-linuxcnc-q...ters?start=20#303239

Ok This was a mess..

First things first.
I did a manual install it's not that scarey, but just easier, on a clean install.

I did edit /etc/apt/sources.list.d/linuxcnc-uspace.list
Changed https to http & changed the end of the line to 2.9-rt

Ok lets get what we need.
In a terminal

We have the packages we need

We have the latest

If we don't remove the doc packages we get errors on installing linuxcnc.

Reboot on the grub screen you may have to go to the advanced options and select the rtai kernel

Long and convulted, installing the docs may throw an issue.

grub-customizer can be used to set the default to the rtai kernel.
Should be under the system heading in the applications menu.

With regard to the Atom......I have a notebook with an Atom N455 1.66GHz and it's basically like wading through molasses. Hopefully yours is to better spec and the parallel offers you some fun.

If you have any more issues just yell/send smoke signals/bang on a drum/or whatever form of communication you prefer, I prefer crayons and a wall. And after being a graffiti cleaner crayon is one of the hardest to remove from most surfaces.

Thanks for the advice! I managed to install RTAI using it

My latency numbers improved, but not as much as I hoped for. I need to look into new motherboard.

I've just moved from the Premt-rt to the rtai kernel, using the above method and uname does show the rtai kernel is loaded, so all well there I think.

LinuxCNC program opens, is there a way to check I do have Linuxcnc for RTAI kernel?

Stepconf wizard opens.

Latency Test does not open.

None of the docs open, I did get this message
"An error occurred. The following details are provided: E: /tmp/apt-dpkg-install-u3Rr2j/00-linuxcnc_1%3a2.9.3_amd64.deb: trying to overwrite /usr/share/applications/linuxcnc-documentation.desktop which is also in package linuxcnc-doc-en 1:2.9.3"

In case it's relevant,  I didn't manage to load linux.image using the dpkg command, so used 'Linuxcnc' in synaptic package manager.

Not sure how to resolve these issues?

Resolved issues by installing via dpkg from the Linuxcnc Downloads page rather than the Synaptic packages, ie followed the instructions above!

Max jitter on Dell Optiplex 980 i3 550 3.2GHz, 16GB ram, 512GB SSD, has dropped from c.60,000 using preemt rt to c.9800 using rtai with everything recommended disabled in BIOS.

So a good result.

Oh wow, nice! Glad you got it going!