Hi -
I'm using my newly enhanced rpctrace to hunt down a few bugs.
Here's a minor one in glibc that shows up like this on "rpctrace /bin/true":
task337(pid1240)->mach_port_deallocate (pn{ 0}) = 0xf ((os/kern) invalid name)
The trick is to get rpctrace to halt the process when it encounters something like that, then gdb shows you right where the problem is. I haven't worked that up into a publishable patch, yet...