I'm trying to run gdb on gcc, but have it follow-fork
and debug into the cc1 subprocess.  I'm using an up-to-date F8.
Here is the transcript of the session:

gdb --args /home/tromey/incremental/install/bin/gcc -O2 -S
/home/tromey/incremental/trunk/gcc/testsuite/gcc.c-torture/compile/20010404-1.c 

(Note that I'm running in Emacs using a special (local) mode,
which I think adds -fullname --annotate=3, in case that matters)

Current directory is ~/incremental/T/
GNU gdb Red Hat Linux (6.6-43.fc8rh)
Copyright (C) 2006 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i386-redhat-linux-gnu"...
Using host libthread_db library "/lib/libthread_db.so.1".
(gdb) set detach-on-fork off
(gdb) set follow-fork-mode child
(gdb) b internal_error
Function "internal_error" not defined.
Make breakpoint pending on future shared library load? (y or [n]) y
Breakpoint 1 (internal_error) pending.
(gdb) r
Starting program: /home/tromey/incremental/install/bin/gcc -O2 -S
/home/tromey/incremental/trunk/gcc/testsuite/gcc.c-torture/compile/20010404-1.c
[Thread debugging using libthread_db enabled]
../../gdb/linux-nat.c:623: internal-error: unknown ptrace event 5
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Quit this debugging session? (y or n) y
../../gdb/linux-nat.c:623: internal-error: unknown ptrace event 5
A problem internal to GDB has been detected,
further debugging may prove unreliable.
Create a core file of GDB? (y or n) n

Debugger exited abnormally with code 1