Re: multi-thread debugging not working

[Daniel Jacobowitz <drow@mvista.com>]

On Tue, Jul 16, 2002 at 04:55:57PM -0700, Lucy Zhang wrote:
> Hi,
> 
> 
> Yes, the newer version of GDB solved the previous problem.
> 
> Now I have a new problem with not being able to debug my multi-threaded
> program. I'm debugging using an ELF core dump that was coverted from another
> format. The program i'm debugging has about 20 threads. It may be because
> the ELF file i'm creating is missing certain information. Right now I'm at a
> loss as to what could be missing which GDB might be looking for in order to
> see the multiple threads. Does anyone have any ideas on how GDB recognize
> threads from an ELF core dump?

There should be a PT_NOTE section (or two or three of them) for every
single thread, containing its registers.  Most GNU/Linux systems at
least do not dump adequate information; you'll have to investigate your
dump format/conversion.



> 
> Below is the output from GDB:
> ----------------------------------------
> /work/lucy/gdb-5.2/gdb > ./gdb
> GNU gdb 5.2
> Copyright 2002 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".
> Setting up the environment for debugging gdb.
> .gdbinit:5: Error in sourced command file:
> No symbol table is loaded. Use the "file" command.
> (gdb) file /work/lucy/lucy1_0524/src/user/elf/vlio_test8.020715.042017
> Reading symbols from
> /work/lucy/lucy1_0524/src/user/elf/vlio_test8.020715.042017...done.
> (gdb) core-file /work/lucy/lucy1_0524/src/user/elf/elf.020715.042017
> Core was generated by `vlio_test8'.
> Program terminated with signal 4, Illegal instruction.
> Reading symbols from /lib/i686/libpthread.so.0...done.
> Loaded symbols for /lib/i686/libpthread.so.0
> Reading symbols from /lib/i686/libm.so.6...done.
> Loaded symbols for /lib/i686/libm.so.6
> Reading symbols from /usr/lib/libpopt.so.0...done.
> Loaded symbols for /usr/lib/libpopt.so.0
> Reading symbols from /lib/i686/libc.so.6...done.
> Loaded symbols for /lib/i686/libc.so.6
> Reading symbols from /lib/ld-linux.so.2...done.
> Loaded symbols for /lib/ld-linux.so.2
> #0 0x40091aa5 in sigset (sig=-1073747472, disp=0x20) at
> ../sysdeps/posix/sigset.c:69
> 69 ../sysdeps/posix/sigset.c: No such file or directory.
> in ../sysdeps/posix/sigset.c
> 
> (gdb) info threads
> * 1 process 1491 0x40091aa5 in sigset (sig=-1073747472, disp=0x20)
> at ../sysdeps/posix/sigset.c:69
> (gdb) thread 0
> Thread ID 0 not known.
> (gdb) thread 2
> Thread ID 2 not known.
> (gdb) thread 3
> Thread ID 3 not known.
> (gdb)
> 
> Thanks,
> Lucy
> 
> 
> ----- Original Message -----
> From: "Daniel Jacobowitz" <drow@mvista.com>
> To: "Lucy Zhang" <lucyz@uclink4.berkeley.edu>
> Cc: <gdb@sources.redhat.com>
> Sent: Tuesday, July 16, 2002 1:23 PM
> Subject: Re: problem loading libpthread.so
> 
> 
> > On Tue, Jul 16, 2002 at 01:17:05PM -0700, Lucy Zhang wrote:
> > > Hi,
> > >
> > > I used GDB to debug an ELF core dump which was converted from a
> different
> > > formatted dump. However when I run GDB I get the following error:
> > > This GDB was configured as "i386-redhat-linux"...
> > > Core was generated by `vlio_test8'.
> > > Program terminated with signal 4, Illegal instruction.
> > > Reading symbols from /lib/i686/libpthread.so.0...done.
> > >
> > > warning: Unable to set global thread event mask: generic error
> > > Segmentation fault (core dumped)
> >
> >
> > > Does anyone know what may have caused the seg fault. I'm not very
> familiar
> > > with GDB at all. So if anyone has any guess or intuitions about the
> cause of
> > > this problem please share.
> >
> > You need to get a newer version of GDB.  Check 5.2, from
> > http://sources.redhat.com/gdb/, and see if that works better.
> >
> > --
> > Daniel Jacobowitz                           Carnegie Mellon University
> > MontaVista Software                         Debian GNU/Linux Developer
> 
> 

-- 
Daniel Jacobowitz                           Carnegie Mellon University
MontaVista Software                         Debian GNU/Linux Developer