Unfortunately, subsequent to the original announcement of an RTAI kernel that works on Debian Jessie, we found that the kernels (32- and 64-bit) both regularly crash the buildbot system. (buildbot is both our continuous integration system as well as our package building system) so those "builders" have been disabled until someone comes up with a solution.
As a result, we aren't able to offer pre-built linuxcnc packages for those configurations at the moment.
It is not clear whether this problem affects "real" systems, because in our buildbot, each OS we build for is running virtualized (by qemu, I think). So at the moment you can download the kernel images from us as .deb packages, but you'll need to do your own (RIP) build of LinuxCNC. To me, it looked a little bit like the error might only occur when running as a VM on a very overloaded host, but I don't know for certain and I haven't installed this kernel on a non-virtual system (or even a virtual one for that matter)
