I have a Sparc 20 running Debian/Potato quite happily with dual
SM71 processors (stays up for weeks on end). The only problem with the
system is that I am unable to get the serial ports to work, either from
the PROM console or from Linux. I am aware of the A/B nature of the serial
port on this machine, and have attempted with known good null modem serial
cables (i.e. they work on Sparc 5s and everything else). I have also
verified the motherboard jumper settings to make sure that the serial
ports are configured for RS232 (and NOT RS422).
If I boot the system w/o keyboard or framebuffer (there is no
VSIMM in this machine), no output ever appears on the serial port, but the
system will boot just fine. Once Linux is booted, w/ or w/o the
keyboard+framebuffer, I can not get any gettys to work on the serial ports
either. It is as if the entire serial port is disabled, or worse just a
black hole for data. :(
So, given that I have checked every bit of hardware and software I
can think of, does any one have any other ideas? I simply want to use the
serial port for the console, removing the need for a keyboard and
framebuffer. Is there some other jumper that I need to set, or some PROM
variable that could disable the serial port like this? I got this system
used and have no clue as to its prior history, especially with regards to
it serial ports. Though I did upgrade the firmware on this system (to
suppor the dual SM71s), but the serial port never worked before that
either.
Lastly, if I can't get the onboard serial port working, is it
possible to add an sbus card with additional serial port to the system and
use one of them as a console? Thanks.