[FFADO-user] systemd jackd service unit xrun on startup (ffado backend)

[Dylan G. <dgl...@gm...>]

Hello, I've written a systemd unit file for jackd that appears to work 
as expected when starting manually via systemctl start jack.service, but 
appears to crash with an xrun on startup.

Here are the contents of the unit file /etc/systemd/system/jack.service:

[Unit] Description=JACK Audio Server After=sound.target [Service] 
User=myusername Group=audio Environment="JACK_NO_AUDIO_RESERVATION=1" 
LimitRTPRIO=95 LimitMEMLOCK=infinity ExecStart=/usr/bin/jackd -d 
firewire -r 44100 -n 3 -p 512 [Install] WantedBy=multi-user.target

This results in the following error when starting the system:

 > systemctl status jack.service ● jack.service - JACK Audio Server   
Loaded: loaded (/etc/systemd/system/jack.service; enabled; vendor 
preset: enabled)   Active: active (running) since Sat 2019-03-23 
18:56:57 PDT; 3min 13s ago Main PID: 953 (jackd)    Tasks: 12 (limit: 
4915)   CGroup: /system.slice/jack.service           └─953 
/usr/bin/jackd -d firewire -r 44100 -n 3 -p 512Mar 23 18:56:57 
planetfunkatron jackd[953]: Copyright 2016-2017 Filipe Coelho.Mar 23 
18:56:57 planetfunkatron jackd[953]: jackdmp comes with ABSOLUTELY NO 
WARRANTYMar 23 18:56:57 planetfunkatron jackd[953]: This is free 
software, and you are welcome to redistribute itMar 23 18:56:57 
planetfunkatron jackd[953]: under certain conditions; see the file 
COPYING for detailsMar 23 18:56:57 planetfunkatron jackd[953]: JACK 
server starting in realtime mode with priority 10Mar 23 18:56:57 
planetfunkatron jackd[953]: self-connect-mode is "Don't restrict self 
connect requests"Mar 23 18:56:58 planetfunkatron jackd[953]: 
1553392618003432:  (ffado.cpp)[  92] ffado_streaming_init: libffado 
2.3.0- built Feb  6 2018 19:14:14Mar 23 18:57:17 planetfunkatron 
jackd[953]: JackFFADODriver::ffado_driver_wait - unhandled xrunMar 23 
18:57:17 planetfunkatron jackd[953]: firewire ERR: wait status < 0! (= 
-1)Mar 23 18:57:17 planetfunkatron jackd[953]: 
JackAudioDriver::ProcessAsync: read error, stopping...

I am guessing that this has something to do with startup order; after 
executing sudo systemctl restart jack.service I notice that the control 
group appears to start the PulseAudio daemon as well:

> systemctl status jack.service      
● jack.service - JACK Audio Server
    Loaded: loaded (/etc/systemd/system/jack.service; enabled; vendor preset: enabled)
    Active: active (running) since Sat 2019-03-23 19:01:55 PDT; 4s ago
  Main PID: 2803 (jackd)
     Tasks: 16 (limit: 4915)
    CGroup: /system.slice/jack.service
            ├─2803 /usr/bin/jackd -d firewire -r 44100 -n 3 -p 512
            └─2823 /usr/bin/pulseaudio --start --log-target=syslog

Mar 23 19:01:56 planetfunkatron jackd[2803]: jackdmp 1.9.12
Mar 23 19:01:56 planetfunkatron jackd[2803]: Copyright 2001-2005 Paul Davis and others.
Mar 23 19:01:56 planetfunkatron jackd[2803]: Copyright 2004-2016 Grame.
Mar 23 19:01:56 planetfunkatron jackd[2803]: Copyright 2016-2017 Filipe Coelho.
Mar 23 19:01:56 planetfunkatron jackd[2803]: jackdmp comes with ABSOLUTELY NO WARRANTY
Mar 23 19:01:56 planetfunkatron jackd[2803]: This is free software, and you are welcome to redistribute it
Mar 23 19:01:56 planetfunkatron jackd[2803]: under certain conditions; see the file COPYING for details
Mar 23 19:01:56 planetfunkatron jackd[2803]: JACK server starting in realtime mode with priority 10
Mar 23 19:01:56 planetfunkatron jackd[2803]: self-connect-mode is "Don't restrict self connect requests"
Mar 23 19:01:56 planetfunkatron jackd[2803]: 1553392916776023:  (ffado.cpp)[  92] ffado_streaming_init: libffado 2.3.0- built Feb  6 2018 19:14:14

Any help would be greatly appreciated.