1. how did you get RTAI to work ? did you use the AUR method?
no, I went the manual way: get kernel sources, get rtai patches. It's a bit long but it works. I think I followed the instructions from the linuxcnc wiki. But I can't remember for sure.
I used kernel 3.8.13 and rtai 4.0. I copied my kernel config from /proc/config.gz.
