> We're going to need more info, try
 > 
 > $ script -c gdb

$ script -c gdb
script: invalid option -- c
usage: script [-a] [-f] [-q] [-t] [file]

I don't know why script needs to be used but this is roughly what I've done:

$ gdb gdb
(top-gdb) set logging on
(top-gdb) cd ~/emacs/src            (to get in the right directory for Emacs)
(top-gdb) set debug target 1
(top-gdb) set debug infrun 1
(top-gdb) run emacs
...
.
(gdb) b Fsplit_window
(gdb) run
Starting program: /home/nick/emacs/src/emacs -geometry 80x40+0+0
...
.

        C-x 2 in Emacs

...
.
Breakpoint 3, Fsplit_window (window=137731057, size=137731057, 
    horflag=137731057) at window.c:3697
3697      if (NILP (window))
(gdb) n
...
.
^C           (kills Emacs)
^C           (kills GDB)
Program received signal SIGINT, Interrupt.
0x401563d4 in poll () from /lib/libc.so.6
(top-gdb) ^D
The program is running.  Exit anyway? (y or n) y

(I'm looking at gdb.base/sigrepeat.exp now.)

Nick