OFW access from linux -> kgdb

[John Gilmore]

> it sounded like there was also some thought that the emphasis
> should be on tools, like kgdb, which can be more general purpose,
> and more widely used and maintained.  to which i'd say, the more
> the merrier -- i'd love to use kgdb regularly, but it requires a
> second machine, and it ties up scarce serial ports.  so OFW is a
> win, for my current uses.

In theory we could make one OLPC kernel debuggable by another OLPC,
just using the WiFi interfaces and "a simple matter of software".

kgdb should be able to use an ethernet, if the Ethernet driver
implements the NETPOLL interface.  I think WiFi counts as Ethernet, at
least if you use ad-hoc mode, or if you can get the interface brought
up (by the usual means) before you need the debugger.  You still need
two machines, unless the kernel you're debugging is running in a
virtual machine.  The machine you run GDB on can be any computer, it
doesn't have to match the one you're debugging.

See:

  http://kernel.org/pub/linux/kernel/people/jwessel/kgdb/index.html

which was readily findable via Wikipedia's "kgdb" entry.

For all I know, OFW has a gdb debug stub in it somewhere, too...

	John
	(I used to maintain gdb, in the distant past.)