Use firewire audio interface with JACK2 in Arch Linux

firewire-audio-interface-jack2-linux.md

• Blacklist firewire sound kernel modules to prevent ALSA and PulseAudio from managing them by creating a file like /etc/modprobe.d/blacklist-snd-firewire.conf:

# This fixes the usage of firewire soundcards with Jack by
# preventing ALSA from handling the device.
# Only modules used for the Edirol FA-66 are blacklisted.
#
# For details refer to:
# https://wiki.archlinux.org/index.php/JACK_Audio_Connection_Kit
# https://github.com/takaswie/snd-firewire-improve/blob/315dcdc4e430d44a6e109a015beecb8515fbe634/sound/firewire/Kconfig

#blacklist snd-fireworks
blacklist snd-bebob
#blacklist snd-oxfw
#blacklist snd-dice
#blacklist snd-firewire-digi00x
#blacklist snd-firewire-tascam
blacklist snd-firewire-lib
#blacklist snd-firewire-transceiver
#blacklist snd-fireface
#blacklist snd-firewire-motu

• reboot or unload the relevant kernel modules with rmmod MODULE_NAME
• Install jack2: pacman -S jack2
• Create the following service unit file in ~/.config/systemd/user/jackd.service:

# ~/.config/systemd/user/jackd.service
[Unit]
Description=JACK daemon for Edirol FA-66 firewire interface

[Service]
Type=simple
ExecStart=/usr/bin/jackd --realtime -d firewire

• jackd -d firewire --help shows you additional options but I had no luck with non-default settings for my Edirol FA-66. Luckily, those default settings are sane.
• reload user systemd daemon: systemctl --user daemon-reload
• start the service: systemctl --user start jackd
• want some log output? Use this: journalctl --user -fu jackd
• Have fun!
• PS: Don't forget to add your user to the audio group! Otherwise you won't get realtime scheduling.

The FA-66 seems to run fine with ALSA as JACK backend if pulseaudio's JACK sink is removed.