I have no idea who to report this to, but I think I have found a glitch in the Sound Blaster Live (emu10k1) driver in linux. I would like some assistance from you cool guys in the world of linux, in getting this reported and fixed.


To reproduce these steps, you will need aplaymidi and rosegarden installed.
Steps to reproduce:

1 Start a midi file playing using aplaymidi, which should be set to use the Sound Blaster live's hardware wavetable synthesizer (most likely port 17:0, or in older kernels maybe 65:0)
2 While this is happening, open Rosegarden. If the computer doesn't freeze, close rosegarden and open it again. After a couple of tries, it ought to freeze the system.

I imagine this is a problem to do with something (in this case rosegarden) trying to open a sequencer connection with the SB live synth while it's already busy with something else (in this case aplaymidi).

Many people still have soundblaster cards, and quite a few use its synthesizer. So I think it's important that this bug gets some attention.
Myself, I'm just a lowly man who uses the UBUNTU LINUX! I haven't the strength or the courage to go into the KERNEL MAILING LISTS and other frightening places.
YOU have the pow0r to help make LINUX a better OS for those of us who use the SOUND BLASTER LIVE (emu10k1)!

I would eport this as a bug in Rosegarden. Possibly Rosegarden is not using lock files correctly. Is this the bug?

http://www.nabble.com/-Bug-148305--N...c11847288.html

In any case here is an explanation of how to report bugs in Rosegarden.

http://rosegarden.sourceforge.net/tu...uidelines.html

--------------------
Steve Stites

Isn't the emu10k1 module made by the folks at Alsa? Maybe they have a mailing list there. I wouldn't be too worried about joining lists - we all have to start somewhere and most of the time they are a great resource.

It's more likely to be a kernel/driver problem, because it results in a complete system freeze. Keyboard lights don't change, ctrl+alt+f1 doesn't work, etc.

Thanks dive. I'll look over the alsa site.

The freeze is occurring in the driver which is part of the kernel. The sound card is supposed to be single threaded, i.e. only one program at a time can play sounds. In your description of the problem you say that you start aplaymidi and then start Rosegarden. The problem is intermittent in that sometimes the problem happens and sometimes it doesn't.

These symptoms point to the driver sometimes collapsing when trying to work on two sound requests simultaneously. Sometimes the timing of the two requests cause the driver to discombobulate and sometimes it doesn't. The driver is not written for simultaneous access from two different threads. The problem is similar to two different programs trying to burn CDs at the same time.

This type of access control problem for exclusive use of a resource is handled by using lock files. So some software in the stack of sound programs is responsible for insuring that the currently running sound application has exclusive control of the sound card. The responsible programs are most likely Rosegarden and aplaymidi. They should obtain exclusive use of the sound card before attempting to use it. If the responsible program is somewhere down the stack from Rosegarden then the Rosganden developers can push the bug report on to the software developers who are supposed to handle the lock files for sound access. Or if Rosegarden is handling the lock files correctly and aplaymidi isn't then the Rosegarden developers can pass the bug on to aplaymidi.

---------------------------
Steve Stites

Then that's still a serious design flaw of either alsa, or linux, or the the driver. Because if someone forgets to handle these lock files in their application program properly, this simple bug in their program brings down the entire system.
And if something wrongly tries to have access to the driver when something else is already using it, the driver should be able to gracefully handle the situation rather than bombing out and taking the entire system down with it.

You are right. The lock files should be handled as far down the stack as possible. The locking logic must be on the Rosegarden and aplaymidi threads but it should be as close to the actual driver as possible. So you have changed my thinking to looking for the bug in software called by Rosegarden and aplaymidi. In any case when Rosegarden is started it should return a "device busy" error.

---------------------------
Steve Stites

You might want to check your sound card settings. I seem to recall that the "full duplex" is not checked by default in the sound card setup dialog on KDE or GNOME.

Shouldn't the driver lock the card? If this is as jailbait told, then you could experience same problems with any audio app and rosegarden (or aplaymidi). You could try and then you'll know which app disrespects locks. Alsa == driver. Driver crash shouldn't crash linux kernel (it was designed to act so, but probably it doesn't mean that it recovers always).