[Qemu-devel] Using GDB with Qemu : No Symbol Table?

[Qemu-devel] Using GDB with Qemu : No Symbol Table?

[Atoosah]

Hi,

-- I'm using qemu version 0.8.2 on linux.  I need some pointers on how
to run qemu with gdb.

[installed_qemu/bin]$./qemu mydisk.img -m 256 -s -S

-- At this point, qemu loads up and waits on port 1234. qemu's console
output is:

Waiting gdb connection on port 1234

-- But, when I run gdb, and try to put a break statement before
continuing, gdb states that there is no symbol table as shown below.
(I don't have a symbol table compiled in the a file, so can't use
"file" command.) The qemu options available to me does not have a -g
option (as I've seen used in some examples).

$gdb vmlinux
(gdb) target remote localhost:1234
Remote debuggin using localhost:1234
0x0000fff0 in ?? ()
(gdb) break main
No symbol table is loaded. Use the "file" command.
(gdb) c
Continuing.

Program received signal SIGINT, Interrupt.
(gdb) list
No symbol table is loaded. Use the "file" command.
(gdb) where
#0 0xc0101040 in ?? ()
#1 0xc01010ac4 in ?? ()
...

-- Any ideas why there would be no symbol table available to gdb? Are
there any steps I'm missing? Do I need to compile qemu differently?

thank you,
Atoosaah

Re: [Qemu-devel] Using GDB with Qemu : No Symbol Table?

[Mulyadi Santosa]

Hi

On Wed, Jun 25, 2008 at 11:41 PM, Atoosah <atoosaah@gmail.com> wrote:
> $gdb vmlinux
> (gdb) target remote localhost:1234
> Remote debuggin using localhost:1234
> 0x0000fff0 in ?? ()
> (gdb) break main
> No symbol table is loaded. Use the "file" command.
> (gdb) c
> Continuing.

try to compile your kernel with CONFIG_DEBUG_INFO=y and
CONFIG_FRAME_POINTER=y. Both will enable gdb to easily resolve symbol
names into addresses and tracking down function call chain in stack
frame.

regards,

Mulyadi.

[Qemu-devel] Using GDB with Qemu : No Symbol Table?

[Atoosah]

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Hi

Thank you for your help, but I think my question was misunderstood.

Debugging the kernel is not my goal. Instead, I want to debug qemu itself.
i.e. I want to be able to add watchpoints/breakpoints to qemu source code.
How do I compile Qemu to enable the symbol table?

My difficulty is that I need to be able to make install my_qemu (i.e. the
installed qemu version). Correct me if I'm wrong, but the -s -S options are
necessary if the goal is debugging the kernel. Is there a patch available,
such as the one provided in
http://www.h7.dion.ne.jp/~qemu-win/DebuggingTips-en.html/ (which seems to be
a rather old link)?

Thanks again.

On Wed, Jun 25, 2008 at 11:41 PM, Atoosah <atoosaah@gmail.com> wrote:
> $gdb vmlinux
> (gdb) target remote localhost:1234
> Remote debuggin using localhost:1234
> 0x0000fff0 in ?? ()
> (gdb) break main
> No symbol table is loaded. Use the "file" command.
> (gdb) c
> Continuing.

try to compile your kernel with CONFIG_DEBUG_INFO=y and
CONFIG_FRAME_POINTER=y. Both will enable gdb to easily resolve symbol
names into addresses and tracking down function call chain in stack
frame.

regards,

Mulyadi.

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Re: [Qemu-devel] Using GDB with Qemu : No Symbol Table?

[Daniel Jacobowitz]

On Mon, Jul 07, 2008 at 05:42:36PM -0700, Atoosah wrote:
> Hi
> 
> Thank you for your help, but I think my question was misunderstood.
> 
> Debugging the kernel is not my goal. Instead, I want to debug qemu itself.
> i.e. I want to be able to add watchpoints/breakpoints to qemu source code.

If you want to debug qemu, why are you loading gdb with vmlinux or
connecting to qemu's gdb server?  You want to debug the qemu binary
itself.

-- 
Daniel Jacobowitz
CodeSourcery