Thanks for the help AutoStatic and others. I'd given up on Jackd on the Pi for a while, but now I'm up and running.
I got the source of jackd from debian experimental, (which contains a patch to disable the problematic code), disabled dbus in the config and built it with dpkg-buildpackage. It was quite straightforward really.I also filed a bug report to Raspbian since I couldn't find one on this issue.
On to other problems; I'm using an el-cheapo USB card for testing purposes, but can't get duplex going without issues. Inputs or outputs only work ok, but duplex just ends in lots of xruns. It kindof works with the -s option to the alsa backend, but audio is quite bad then, with intermittent crackle.
I'm not sure if it's a driver issue or if it's to do with the environment on the Pi. (The card is listed as a CM109 in lsusb, uses the CM109/snd_usb_audio driver, and looks a lot like the "HF209-B" from this site:https://sites.google.com/site/bifferboa ... ound-cards
It was dirt cheap so no major loss, but I need to find something that works well with duplex and jackd (and hopefully doesn't cost an arm and a leg).
Any suggestions of a USB card that works well with Jackd and duplex on the Pi?
Maybe I should start another thread about it?