[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.


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