the breakpoint of gdb

the breakpoint of gdb

[s88]

Hi all:

Could anyone tell me something about how the gdb to achieve the the
breakpoint function in different platform?
I heard the gdb's breakpoint implement on the X86 platform is by the
instruction patch. It sounds interesting!! I want to know more
details.
Any reference info, web page, books are welcome.


Thanks,

Dave.

-- 
System  on Chip Design  Lab.
Dept. of Computer Science and Information Engineering,
National Chung Cheng University
E-mail : s88.tw@acm.org

Re: the breakpoint of gdb

[Michael Snyder]

On Sat, 2006-10-14 at 01:53 +0800, s88 wrote:
> Hi all:
> 
> Could anyone tell me something about how the gdb to achieve the the
> breakpoint function in different platform?

Thru a platform_specific method (function pointer) called
"target_insert_breakpoint".  Each target or platform defines
this function as appropriate.

Look for "target_insert_breakpoint" in breakpoint.c and target.h, 
then grep for "to_insert_breakpoint" in *.c.

> I heard the gdb's breakpoint implement on the X86 platform is by the
> instruction patch. It sounds interesting!! I want to know more
> details.

Yes, the most common method is to insert a trap instruction
(or similar) into memory.  See function "memory_insert_breakpoint"
in mem-break.c.  Again, each target platform has to define the
appropriate bit-pattern or instruction to be inserted.


> Any reference info, web page, books are welcome.

Hah.  If you write that book, you will become famous.   ;-)

Re: the breakpoint of gdb

[ramana.radhakrishnan]

> Any reference info, web page,> books are welcome.

Atleast as a student "How Debuggers Work" was useful and interesting to
read. However to paraphrase my compiler guru.

In theory there is no difference between theory and practice :)

Good luck.

-Ramana

>
>
> Thanks,
>
>
> Dave.
>
>
> --
> System  on Chip Design  Lab.
> Dept. of Computer Science and Information Engineering,
> National Chung Cheng University
> E-mail : s88.tw@acm.org
>
>