Re: Debugging fork-ed processes woes

[Michael Snyder]

Frank Schaefer wrote:
> 
> Hi there,
> 
> Seems 'set follow-fork-mode' doesn't work for gdb-5.0. See the
> following.

Hi, 

I'm afraid "follow-fork" was only implemented on HPUX.
Sorry for the falsely raised expectations...
Perhaps we should do something about hiding those HP-only
features from non-HP users.

Michael


> 
> # gdb daemon
> GNU gdb 5.0
> Copyright 2000 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 "i686-pc-linux-gnu"...
> (gdb) b 18
> Breakpoint 1 at 0x8048899: file daemon.c, line 23.
> (gdb) run
> Starting program: /v_dsk/home/p10209/Tests/daemon
> 
> Breakpoint 1, main () at daemon.c:23
> (gdb) n
> ..
> (gdb) n
> 67      Childpid = fork();
> (gdb) show follow-fork-mode
> Debugger response to a program call of fork or vfork is "parent".
> (gdb) set follow-fork-mode child
> (gdb) show follow-fork-mode
> Debugger response to a program call of fork or vfork is "child".
> (gdb) n
> 69      sleep( 10 );
> (gdb) print ChildPid
> $1 = 3290       *********************************
>                 ???!!!!!!!!!!!!!!????????????????
> 
> Seems, we were following the parent - weren't we?
> 
> I've configured gdb with:
>         # ./configure           # ( no switches )
> 
> My compiler is GCC-2.93.3 with the glibc-2-patch applied.
> I use binutils-2.11, glibc-2.2.4 and I'm running kernel-2.4.16.
> 
> BTW: The sleep right after the fork() is there, to give me the time, to
> attach a second instance of gdb to the child process.
> If I do so, both processes crash at random locations due to different
> signals ( mostly segfault and sometime illegal instruction ).
> If I run the server and client outside of the debugger, all goes fine.
> 
> Am I missing something?
> Regards
> Frank