rtf device problems on 64-bit RedHat

[Paolo Mantegazza]

Jim Pisano wrote:
> In a previous posting, I had discussed problems I'm having with RTAI FIFO device problems. I have learned some more, but am still having some difficulty.
> 
> I'm using 64-bit RHEL 4, RTAI magma, kernel 2.6.20.7, gcc 3.4
> 
> When I boot my computer, the rtf device files correctly appear in /dev/ (note that they are defined in /etc/udev/devices as per the RHEL 4 rules):
> 
> crw-rw-rw-  1 root root 150,   0 Apr 30 15:44 rtf0
> crw-rw-rw-  1 root root 150,   1 Apr 30 15:44 rtf1
> crw-rw-rw-  1 root root 150,   2 Apr 30 15:44 rtf2
> crw-rw-rw-  1 root root 150,   3 Apr 30 15:44 rtf3
> crw-rw-rw-  1 root root 150,   4 Apr 30 15:44 rtf4
> crw-rw-rw-  1 root root 150,   5 Apr 30 15:44 rtf5
> crw-rw-rw-  1 root root 150,   6 Oct 24 08:53 rtf6
> crw-rw-rw-  1 root root 150,   7 Apr 30 15:44 rtf7
> crw-rw-rw-  1 root root 150,   8 Apr 30 15:44 rtf8
> crw-rw-rw-  1 root root 150,   9 Apr 30 15:45 rtf9
> 
> But when I install 3 kernel modules:
> rtai_hal
> rtai_sched
> rtai_fifos
> 
> All 64 rtf devices are created (rtf0 - rtf63) & their permissions have changed to:
> 
> crw-------  1 root root 150,  0 Apr 30 15:44 /dev/rtf0
> 
> I am unable to use these fifos because their permissions are wrong. Then when I rmmod rtai_fifos, the devices in /dev/ disappear altogether!
> 
> Something is wrong, but I get no log messages in /var/log/messages about any problems. I can manually create the /dev/rtfX files w/ the standard mknod script, but the problem still appears when I load & unload rtai_fifos.ko
> 
> -Jim


Can you see them, e.g.. "ls",  by waiting a bit after inserting the 
related module?

Fifos are menaged as devfs, os they are created dynamically by 
rtai_fifo. The annoyance I can see is that they do not live as /drv/rtf* 
immediately after their creation, but takes some time to appear with 
"ls", which is a bit annnoying in fast testing. My choice is to launch 
the, many time here reported, script:

for n in `seq 0 9`; do
         f=/dev/rtf$n
         if test \! -c $f; then
                 mknod -m 666 $f c 150 $n
         fi
done

when I insert the related module to have them readied immediately.

Notice that at rmmod they disappear and so the above script is repeated 
   at any insmod.