>> I just compiled 23.1.94 on OSX leopard with-x and it freezes in
>> following these simple steps:

>> 1. M-x gdb
>> 2. att TAB

I reported this problem in 
<http://debbugs.gnu.org/cgi/bugreport.cgi?bug=5404>.  Nick Roberts was
kind enough to guide me through some diagnostic exercies.  Perhaps
our most interesting finding was message 34.

    http://debbugs.gnu.org/cgi/bugreport.cgi?bug=5404#34

The hang appears to be (at least somewhat) related to the onlcr tty
setting for the gdb subprocess.  And there may be some overlap with
the EOL conversions that YAMAMOTO Mitsuharu noted.

The workaround I've been using on Mac OS X is

    Within the *gud-PROGRAM* buffer, run "shell stty -onlcr" after the
    target program starts running, and don't try to use symbol
    completion before the target program starts.

The GDB is Apple's GDB.

I tend to move around between two Mac OS systems, and two GNU/Linux
systems.  5404's behavior is reliably reproducible on Mac OS X 10.4
and 10.6 with Apple's GDB.  I've never seen 5404's symptoms occur on
GNU/Linux.  I don't know whether 5404's behavior appears on Windows.

Finally, I haven't had a chance to compile 23.1.94 yet (still using
23.1.93).  So I can't say if any of 5404's behavior no longer applies
to 23.1.94.

Steve