[linux-audio-user] Jack and SHM

Christophe Vescovi vescovi at lpsc.in2p3.fr
Fri Jan 23 03:32:37 EST 2004


Jack O'Quin a écrit :


> I sometimes run POSIX shm on my Linux system for testing purposes to
> make sure it continues working.  As far as I can tell, it works fine.
> The MacOSX port uses POSIX shm exclusively.
> 
> An earlier POSIX shm implementation worked, but not reliably.  This
> was blamed at the time on bugs in the Linux kernel.  I have not
> observed these problems on my system, but they were the reason why
> Paul decided to make System V shm the default on Linux.  There were
> also install problems due to the requirement that users create an
> /etc/fstab entry of type tmpfs for /dev/shm.
> 
> It may be that newer kernels have a more robust POSIX shm support.
> Or, perhaps the present JACK shm implementation not longer stresses
> whatever component was failing before.  Or, maybe I just haven't run
> it enough to notice, yet.  :-)
> 
> The problems that you mention are serious and should be reported in
> the JACK bug database, <http://jackit.sourceforge.net/mantis>.

Well, as suggested by Steve, I tried to traced the problem yesterday. 
Since I need to re-compile jack I have update my CVS tree, compile why 
SysV shm and it works !!!!

First time I had this problem was in September with jack 0.80.0, before 
I was not using the -R option, after I was using POSIX shm. The error 
message was issued only when a client want to connect to jack.

Anyway, the problem seems to be fixed, and for me JACK shm 
implementation seems to be stable both with POSIX and SysV shm.

Regards,
Christophe




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