Re: Multiple breakpoint issue when debugging loadable kernel module

[Vimal <j.vimal@gmail.com>]

Hi,

With some suggestions from IRC folks sergiodj and SamB, I ran a git
bisect on the HEAD of git://sourceware.org/git/gdb.git.

It seems like the first bad commit is:
2cdbbe44126601596aad7891de05cb7fc6bb21c8, which seems pretty big
~6000lines.

Quoted below is my first mail to the list, with few details about the
problem.  Also, here's an output from an actual run:
http://pastebin.com/4PhDAHwW...

Tom Tromey: is this a known issue?

Thanks,
--
Vimal


On 23 October 2011 20:16, Vimal <j.vimal@gmail.com> wrote:
> 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
>



-- 
Vimal