Compiling realtime kernel

Yes I know that it tells me to install python3.6 or higher. Nut I have 3.9.9 installed and I even uograded it to 3.10

I'm running ubuntu with cinnamon desktop
It is not a fresh install. It is the system I had for other things and I'm just messing with linuxcnc and ethercat
 

So what does python3 -V report?
 

python - - version reports 3.10
That is why I am confused

Funny, I've been playing with ethercat too!

Personally, I would regroup and follow these instructions
www.qtpyvcp.com/install/bullseye.html
It will add a few extra dependencies  for qtpyvcp you may not need but you never know...

I have a ethercat WIP project documented here with install instructons.
github.com/rodw-au/linuxcnc-cia402

Nice project! Currently I' trying to play with some Beckhoff I/O cards but I need to get linuxcnc up and running. In the past I newer had problems with building Linuxcnc-dev but Jammy seems to give me problems.

Yeh, the move to Python 3 has made it difficult to build from source and I had similar problems that broke configs on Linux Mint because the dependencies changed.

So my solution was to install an OS that only had Python 3.7 or higher and no Python 2.7 and also had a PREEMPT_RT package. I also  needed to get some newer network drivers that were in the 5.10 kernel.

In fact I adopted Bullseye while it was still testing branch.

I'm going to start from scratch... Can you advise me on kernel version best for ethecat. I mean what kernel do you use?

Do you know how to control an EL2809 with "ethercat soe_write"?
ethercat slave reports

0 0:0 PREOP + EK1100 EtherCAT-Koppler (2A E-Bus)
1 0:1 PREOP + EL4132 2Ch. Ana. Ausgang +/-10V, 16bit
2 0:2 PREOP + EL1809 16K. Dig. Eingang 24V, 3ms
3 0:3 PREOP + EL2809 16K. Dig. Ausgang 24V, 0.5A