Emulating a Cyclades/Annex

[Michael ODonnell]

OK - I figured out how to relay traffic between a serial
port and a network-attached process - I thought it'd be
simple, but didn't figure it'd be THIS simple.  On SystemB
(the intermediate system with a serial port connected to the
system being debugged [SystemA] and which is also expected to
field network connections from SystemC that are to be routed
to SystemA via the serial port in question) I just say:

 socket -l -s somePortNumber </dev/ttyS0 >/dev/ttyS0 2>&1

...which will start up a server that routes all traffic from
anybody (one at a time) who opens a socket on somePortNumber
directly to /dev/ttyS0.  So, on SystemC where I have built
the kernels in question and have my kernel source codes,
I start GDB and say:

  target remote SystemB:somePortNumber

...and then on SystemA (whose ttyS1 is connected to SystemB's
ttyS0) where I'm running a kernel that's had the KGDB patches
inflicted upon it, I start my KGDB-patched kernel with these
items on the command line:

  gdb gdbttyS=1 gdbbaud=115200

which arranges for an early KGDB breakpoint, mentions
/dev/ttyS1 as the port to use and 115200 as the baud rate.