Re: [Rosegarden-user] Thorn, exclusive use of ALSA Midi

[D. M. M. <mic...@ro...>]

On Friday 22 January 2010, Alexander Methke wrote:

> Linux stubuntu 2.6.31-9-rt #152-Ubuntu SMP PREEMPT RT Thu Oct 15
> 13:22:24 UTC 2009 x86_64 GNU/Linux

I have the same kernel, and...

> amidi -p hw:1,0,3 -d
> ALSA lib rawmidi_hw.c:233:(snd_rawmidi_hw_open) open /dev/snd/midiC1D0
> failed: Device or resource busy
> cannot open port "hw:1,0,3": Device or resource busy

...if I start Rosegarden, allowing Rosegarden to connect to my USB MIDI 
dongle, then I can repeat the result you just had.  "Device or resource busy."

I can still "sniff" the device with KMidimon just fine, but not with amidi.

Now if I try the same experiment with a non-USB MIDI interface, there is no 
blocking, even using amidi.

Weird.

> Will check later if 1.7.3 acts the same on -rt kernel.

Running 1.7.3 doesn't cause blocking on the USB MIDI dongle for me here, using 
the same kernel.

This really is a difference, although I'm not aware of anything we've done 
that might remotely hint at an explanation where the difference is coming 
from.

I don't think there's much we can do about this unless someone remembers 
tinkering with something in the ALSA driver stuff.  And/or maybe there's some 
remote chance that some part of the difference is due to our completely new 
and redesigned device manager.  I doubt the device manager does anything low 
level, but possibly it uses some different sound driver connect method from 
what the old one did.

No idea there, just wild speculation without any attempt at investigation.
-- 
D. Michael McIntyre