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For the past few weeks, I've been using QJackCtl everyday to start and stop JACK while I record music, and it's worked perfectly. Just recently though (within the past two days) its stopped working. My hunch is that it has something to do with a recent update in Arch... but I'm not sure which one. I thought maybe it was the recent ALSA update, but I re-installed the previous version of ALSA and that didn't help.
Here's what the Messages window in QJackCtl says every time I try to start JACK:
22:21:36.248 JACK is starting...
22:21:36.248 /usr/bin/jackd -R -dalsa -dhw:1 -r48000 -p128 -n2 -m -Xseq
22:21:36.288 JACK was started with PID=2925.
jackd 0.109.2
Copyright 2001-2005 Paul Davis and others.
jackd comes with ABSOLUTELY NO WARRANTY
This is free software, and you are welcome to redistribute it
under certain conditions; see the file COPYING for details
JACK compiled with POSIX SHM support.
loading driver ..
can't load "/usr/lib/jack/jack_alsa.so": /usr/lib/jack/jack_alsa.so: failed to map segment from shared object: Bad address
cannot load driver module alsa
libgcc_s.so.1 must be installed for pthread_cancel to work
22:21:36.392 JACK was stopped successfully.
22:21:36.392 Post-shutdown script...
22:21:36.393 killall jackdI've tried running JACK from the command-line like this:
/usr/bin/jackd -p 128 -T -d alsa -n 2 -r 48000 -p 1024 -d hw:1,0and it seems to work okay, although its not as convenient as using QJackCtl and it may be my imagination, but I noticed that Ardour and JAMin crashed a few times when I ran them after starting JACK this way.
Does anyone know what's going on here?
edit: So I determined it's the "-R" flag for realtime scheduling that is causing the problem. I guess that means it was probably a recent kernel update... Am I going to need to just reinstall the previous kernel version or a realtime kernel, or is there something else I could try?
Last edited by gotsomeideas (2009-02-17 07:39:52)
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Install a realtime patched kernel...I still use 2.6.24 because it works. Welcome to the complete PITA known as linux audio.
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It looks like the latest update of the kernel (2.6.28.5-1) fixes the problem, I can start JACK in realtime again.
By the way, while I haven't recorded any major projects yet, I haven't found it necessary to use a realtime patched kernel... even when running JACK with a sample rate of 48000 and Frames/Period set at 64 (not sure if either of those things actually matter). Maybe not using a realtime patched kernel becomes more of a pain with very large projects, but if you haven't tried using an unpatched kernel recently, you might want to give it a shot.
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