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Here are some answers to frequently asked questions regarding z8530drv-2.4...
vy 73,
Joerg Reuter ampr-net: dl1bke@db0pra.ampr.org
AX-25 : DL1BKE @ DB0ACH.#NRW.DEU.EU
Internet: jreuter@lykos.oche.de
* I have a question...
Read the documentation included in this package, read this FAQ. If
your problems cannot be solved, feel free to ask me. If you find
something wrong, _tell me_, please don't complain to others. Please
report bugs, I'll fix them as soon as possible.
* I tried to compile version 2.4 of this driver with Linux kernel 1.3.x or
prior and it failed.
Try Linux kernel version 2.0.0 or higher. Note that some things may
change in 2.1.x and the driver may or may not compile...
* I tried the utilities included in your package with the driver included
in the Linux 2.0.0 (or prior) kernel source. They don't work.
The ioctl-codes have changed. Upgrade linux/drivers/char/scc.c
and linux/include/linux/scc.h with the versions in this package.
* Sccinit complains about a missing /etc/z8530drv.rc but it's there...
No, sccinit complains about /etc/z8530drv.conf missing. Just rename
/etc/z8530drv.rc to /etc/z8530drv.conf.
* Sccinit complains about "slip" unsupported now...
Ignore it or remove the entries in /etc/z8530drv.conf.
* Sccstat shows that I've got NoSpace errors. What's that?
Ignore it if you are running IP mode datagram, the value just
says that a tx frame had to be discarded. If the value is
very high and you are using IP virtual connect mode, or you
aren't using IP over AX.25 at all, increase the amount of
transmission buffers.
* Sccstat shows TxErrors. What exactly does this mean?
Either a program that is using the TTY mode sent a bogus KISS frame,
or (more likely) 'maxkeyup' expired. If you are using IP in datagram
mode you should increase TCP IRTT (see 'man route') and perhaps
'maxkeyup', too.
* Maxkeyup behaves funny, the first time the PTT stays up for
'maxkeyup' seconds and the driver resumes transmission after
'mintime' correctly, the second time it goes down after few
seconds, starts transmission again immediately and keys down
after three seconds again.
Avoid the driver running into transmission timeouts, if possible
(see last question). This phenomena is a bit complicated to
explain, basicly the hardware watchdog for RTS on your MODEM
interferes with the software watchdog. It is not for the short
drop of the PTT, though. But: something is wrong with the timing
parameters of the network or link layer if you see this behaviour.
* I'm getting the message
z8530drv: rx buffer pool for scc3 empty
what's wrong?
Ignore it. You received more frames the AX.25 layer can handle and
the oldest one was discarded. If you get bombarded with this message
increase the amount of receive buffers.
* Why are you using your own buffer concept anyway?
To keep things portable to other OS. I'm still dreaming of a
port to OS/2, but if I could only find the time... I dropped
the own buffers and the KISS TNC emulation in z8530drv-3.0,
though. Note that z8530drv-3.0 isn't available for Linux 2.0.
Perhaps someone else has the guts to port it back from 2.1
kernels to 2.0, but not me.
* The driver does not find the SCC ports.
Check the command and data register addresses.
* The register addresses are correct, it still does not find the ports.
You are using a PE1PET card, right? This, and some other concepts,
"forget" to delay the IORDY signal, thus the driver must insert
some wait states itself. #define SCC_DELAY in scc.c. This is not
defined by default, I am not willing to do the dirty work for
lazy hardware designers.
* Help, the driver finds my card, but it won't generate interrupts.
Are you sure you specified the right IRQ? Have you tried to #define
SCC_DELAY?
* On transmission the PTT remains keyed for maxkeyup seconds,
sccstat shows exactly one tx interrupt. Receive is okay.
Check the "clock" entry in /etc/z8530drv.conf. You probably
specified the wrong clock source. Try "DPLL" for a start.
If this doesn't help, #define SCC_DELAY in scc.c.
* The PTT only occasionally remains keyed for maxkeyup seconds,
everything else seems to be okay, apart from some transmission
underruns
This appears to be a bug of the Z8530. It sometimes doesn't
generate the ABORT interrupt when an underrun occurs.
* Other stations sometimes have problems to decode my frames. Under
DOS everything is okay. Sccstat shows nothing special.
Increase txdelay and tailtime by 1 (10 msec). This has technical
reasons. Linux has a timer granulity of 10 msec (at least for
i386 architectures), thus setting "tailtime" to 10 msec means
the timer routine gets called with the next timer tick, which
happens most likely before the 10 millisecods have expired.
* Axattach complains about "TIOCSETD: Invalid argument"
You forgot to compile SLIP into the kernel (or the "insmod slip").
Why are you using the KISS TNC emulation anyway? Z8530drv supports
network devices now.
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