[nos-bbs] Ubuntu 9.10 issues and tip....

Chris kc2rgw at gmail.com
Sat Feb 13 13:17:49 EST 2010

So I've had some rather inconsistent issues with Ubuntu 9.10 using
both the native linux ax.25 utlities and JNOS2.  All using the user
space soundmodem utility compiled from latest.

I had a 'sliding' window issue where the packet would either be
foreshortened or cut off, regardless of some rather long experimental
txdelay and txtail settings.  It feels like the OS is randomly
delaying the generation of the packet data.  So the radio will key up
but randomly either send the packet just fine, or cut it off on the
beginning or the end of the packet.

What I discovered is that on a clean system boot, a single bring up of
the 'packet engine' as it were, everything works just great with
either native linux utils or JNOS2.  I had been doing a lot of
fiddling around so I had been bringing the soundmodem interface up and
down multiple times on the same boot and swapping between the linux
native mode and JNOS2.  I tried this with a start and stop script that
both did and didn't unload and load the kernel modules with no
difference in behavior.  Messing with ax.25 params on the fly didn't
seem to make any difference either.

I'm certain there weren't any double instances of anything running.
The script checks for this and Ive manually checked for it.

What the actual root cause is, I have no idea, but I've observed
issues with this going back to Ubuntu 6.x releases and have not tried
with any other distributions.  So I have no clue if it is peculiar to
Ubuntu or not.  I just know that the easy solution is to simply only
bring up packet ops once per boot session and reboot if I wish to swap
anything around.

If I just had to guess, I would guess that the ax.25 kernel modules
are not really cleanly unloading even if lsmod is showing they have
been removed.  Logically I'm not sure of any other reason that would
cause this seeming loop in the timing of the packets.

My soundcard hardware is a Tigertronics Signalink USB, though I doubt
it is anything to do with that in and of itself.

73      de     Chris       KC2RGW
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