breakpoint on non-function symbol

breakpoint on non-function symbol

[Bahadir Balban]

Hi,

Is it possible to put a breakpoint on a symbol that is not a function?

I have two elf images, the first is a loader that contains the second
image in itself. I want to refer to a symbol defined in the second
from the first. To achieve that, I extracted the symbol from second
and defined it as a variable in the linker script of the first. When I
break on  the symbol gdb complains its not a function. I could
possibly define it as a function in assembler but I've done enough
tweaks; don't want to add more unless you have a better suggestion.

Thanks,
Bahadir

Re: breakpoint on non-function symbol

[Andreas Schwab]

"Bahadir Balban" <bahadir.balban@gmail.com> writes:

> Is it possible to put a breakpoint on a symbol that is not a function?

You can put a breakpoint at any address with the "break *ADDR" syntax.

Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab@suse.de
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
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"And now for something completely different."

Re: breakpoint on non-function symbol

[Bahadir Balban]

On 2/1/07, Andreas Schwab <schwab@suse.de> wrote:
> "Bahadir Balban" <bahadir.balban@gmail.com> writes:
>
> > Is it possible to put a breakpoint on a symbol that is not a function?
>
> You can put a breakpoint at any address with the "break *ADDR" syntax.
>
> Andreas.


The problem is the address is not known in advance, so I had to rely
on the symbol. Anyway, I fixed it in assembler by:

.global symname;
.type symname, function;
.equ symname, addr

rather than including it in the linker script.

Thanks,
Bahadir

Re: breakpoint on non-function symbol

[Daniel Jacobowitz]

On Thu, Feb 01, 2007 at 11:26:34AM +0000, Bahadir Balban wrote:
> The problem is the address is not known in advance, so I had to rely
> on the symbol. Anyway, I fixed it in assembler by:
> 
> .global symname;
> .type symname, function;
> .equ symname, addr
> 
> rather than including it in the linker script.

That works, or you can take advantage of what Andreas suggested:

set $var = &symbol
break *$var

-- 
Daniel Jacobowitz
CodeSourcery

Re: breakpoint on non-function symbol

[Bahadir Balban]

On 2/1/07, Daniel Jacobowitz <drow@false.org> wrote:
> That works, or you can take advantage of what Andreas suggested:
>
> set $var = &symbol
> break *$var
>
> --
> Daniel Jacobowitz
> CodeSourcery
>

Ah, ok. That's the trick I was hoping to learn.

Thanks,
Bahadir