debugging the automounter

debugging the automounter

[Philip Ong Jr.]

Are there any good links on how to go about setting up debugging the 
automounter using the gdb?

I’m running rhel3 and trying to figure out an automounter problem. I’ve 
installed the debuginfo package so the binary won’t be stripped.

Does the debuginfo package install another binary to debug the 
automounter using gdb because the binary looks stripped to me…?

# file /usr/sbin/automount
/usr/sbin/automount: ELF 32-bit LSB shared object, Intel 80386, version 
1 (SYSV), stripped

This is NOT stripped…but I’m not sure what this is used for or how to 
use it…
# file /usr/lib/debug/usr/sbin/automount.debug
/usr/lib/debug/usr/sbin/automount.debug: ELF 32-bit LSB shared object, 
Intel 80386, version 1 (SYSV), not stripped

Basically, I’d like to get to the point where I can have an non-stripped 
automounter and how to verify it is not stripped or how to build and 
debug it.

#gdb /usr/sbin/automount
GNU gdb Red Hat Linux (6.3.0.0-0.30.1rh)
Copyright 2004 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"...(no debugging 
symbols found)
Using host libthread_db library "/lib/tls/libthread_db.so.1".
(gdb) quit

#uname -a
Linux l-sim-33-075 2.4.21-53.ELsmp #1 SMP Thu Feb 21 19:01:38 EST 2008 
i686 athlon i386 GNU/Linux

# automount -V
Linux automount version 4.1.3-216

# rpm -qa | grep autofs
autofs-4.1.3-216
autofs-debuginfo-4.1.3-216

I’d appreciate any help.

Thanks
Phil

Re: debugging the automounter

[Marc Weber]

Hi Phil,

first of all why don't you put the question why you need the debugger at
all? What makes you debugging autofs?

You're faced with PIE ( "position independent executable" )
Have a close look at the configure options and or the make flags.
I think you can switch it off. Also there are gdb versions which can
debug PIE. However I didn't suceed compiling them ( I didn't try very
hard)

HTH - good luck
Marc Weber

Re: debugging the automounter

[Jeff Moyer]

"Philip Ong Jr." <pongjr@gmail.com> writes:

> Are there any good links on how to go about setting up debugging the
> automounter using the gdb?

Debugging autofs version 4 with gdb is a tough proposition as many of
the operations performed by the automounter involve forking off another
process.  We mostly rely on the debug logs for understanding aberrant
behaviour.  gdb is can be useful when we get a core file, though.

> I’m running rhel3 and trying to figure out an automounter
> problem. I’ve installed the debuginfo package so the binary won’t be
> stripped.

The list of things I ask for when trying to resolve bugs can be found
here:

  http://people.redhat.com/jmoyer/

Look at the text under "Filing bug reports."

Cheers,
Jeff

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Re: debugging the automounter

[Fabio Olive Leite]

Olá!

On 2010-01-21 Philip Ong Jr. wrote:
> 
> Does the debuginfo package install another binary to debug the 
> automounter using gdb because the binary looks stripped to me…?

The debuginfo package installs an ELF file containing the debug
sections that were stripped off the binary, but not a new full binary.

So the stripped binary goes in the normal package, and you add the
debug symbols to your system with the debuginfo package when you need
them. Then you tell gdb to look at those files for symbol information
for the binary you want to debug.

Cheers,
Fábio Olivé
-- 
ex sed lex awk yacc, e pluribus unix, amem
na matemática das idéias, permuta é igual a adição
e um debate inteligente implementa a multiplicação

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