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From: Vimal <j.vimal@gmail.com>
To: gdb@sourceware.org
Subject: Multiple breakpoint issue when debugging loadable kernel module
Date: Mon, 24 Oct 2011 02:20:00 -0000	[thread overview]
Message-ID: <CAK3Ji13etC=V-mVsbTYLOrTa4ErgaCF8xd+QPU1gtDbngdJpZw@mail.gmail.com> (raw)

Hi,

I have a loadable kernel module, and I am facing issues when setting
breakpoints.

I am using gdb 7.3.1 from ftp://ftp.gnu.org/gnu/gdb.

1. I start the kernel under qemu-kvm and load the kernel module.  The
kernel module was compiled with CFLAGS=-O0 -g

2. I generate the add-symbol-path command by using section address
information from /sys/module/$mod/sections/.*

3. I enter the add-symbol-path command into gdb, which is connected to
qemu's gdb stub via "target remote" command.

4. After loading the symbols, I do: "info line function" and am able
to see the function name's line number.   Also, "list function" shows
the source code from the correct file.

5. I do "break function", I see this message:
    Breakpoint 1 at address (2 locations)

After the last step, if I run "info line function", I see "No line
number information available for address..."

When I type "info break", I see the two breakpoints inserted at
"function+4" and "function+31".

This error does not happen in gdb-7.1.   The reason I am using
gdb-7.3.1 is that I want to use gdb.Breakpoint from a python script.

Is there a way to fix this error?   Why are two breakpoints being set?
  This error happens across a few kernel modules that I tested.

Thanks,
-- 
Vimal

             reply	other threads:[~2011-10-24  2:16 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-10-24  2:20 Vimal [this message]
2011-10-24 14:11 ` Vimal
2011-10-26 12:25 ` Vimal
2011-10-27  0:22   ` Jan Kiszka
2011-10-27  0:43     ` Vimal
2011-10-27  7:21       ` Jan Kiszka
2011-10-27 14:59         ` Vimal
2011-10-27 16:12           ` Jan Kiszka
2011-10-28  0:16         ` Tom Tromey
2011-10-31 17:20           ` Jan Kiszka
2011-10-27 19:38     ` Tom Tromey
2011-10-28  3:40       ` Vimal
2011-10-28 21:07         ` Vimal
2011-10-31 17:18           ` Jan Kiszka
2011-10-31 21:33             ` Tom Tromey
2011-11-01 15:32               ` Jan Kiszka
2011-11-01 20:13                 ` Jan Kratochvil
2011-11-05  2:07                   ` Vimal
2011-11-05  5:39                     ` Jan Kratochvil
2011-11-08  0:33                   ` Jan Kratochvil
2011-11-05  2:10             ` Vimal

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