Linuxcnc start disables Parallel port of PCI Express card

Hi Forum,

I am chasing a weird issue. I recently got a new old PC with great latency for software stepping. I have a running set up with 2 parallel port cards one of them a pci express card.

I installed a clean version of LinuxCNC, copied the config files and added the new address of the parallel port card. The card is recognized from linux as active.

As soon as I start LinuxCNC the card is switched to disabled. I tried to change the /sys/bus/..../enable file. The file still has a 1 even if the port shows with lspci -vv disabled. I can't change the file at all, even as root I am not able to change the file it says file is locked. chmod 777 on this file did not help either.

I don't know why that happens. Due to a dual boot set up I have on this PC I had to install linuxcnc a few times until I had the move cleaned. Meanwhile I had it working when I used UEFI instead of leagcy bios. But with UEFI Linux sometimes the pci express card wasn't seen at all and only showed up when I unpluged the power cord of the PC.

This is so frustrating.

If I just simply clone the old linuxcnc 2.9.3 with a 4.xx Kernel all works. But the fresh installed linuxcnc does not work.

Might be worth looking at dmesg just after starting linuxcnc
So linuxcnc aborts running the config ?

Does linuxcnc report anything ?

When I wanted to post the dmesg output, of course it worked. Will keep an eye on it and let you know if it stops working again.