[LAU] jackd in RT mode at boot

Hello, I need to start jackd server in realtime mode on boot for an audio embedded Linux based project. However it seems that for OS using PAM like Debian, it's impossible to get RT priorities for the predefined jackd user during the boot. I know that starting jackd on boot is something deprecated on most distributions for security reasons. But, for an embedded system, I think this makes sense as no other user will ever log in. So, here's my question : how to get RT priorities for non-root users on boot for jackd 0.118 or 1.9.5 ? Thanks for help, Cheers, Guillaume Pellerin PS : of course, on my system, the jackd server is working perfectly in RT mode when the user log in and manually start the daemon, even in sudo mode..