Re: HW breakpoint on Linux x86 native

[Michael Eager <eager@eagerm.com>]

On 07/16/2012 11:43 AM, Jan Kratochvil wrote:
> On Mon, 16 Jul 2012 20:17:43 +0200, Michael Eager wrote:
>> When running a local process, the target vector is different,
>> created by init_exec_ops() in exec.c.  This defaults to
>> to_can_use_hw_breakpoint = reply_zero().
>>
>> RH has a patch which forces the test in their gdb-7.3.1 release:
>
> http://pkgs.fedoraproject.org/gitweb/?p=gdb.git;a=blob_plain;f=gdb-bz541866-rwatch-before-run.patch;hb=master
>
> It seems to be fixed in FSF GDB since 7.4 by:
>
> [RFA 2/3] Demote to sw watchpoint only in update_watchpoint
> http://sourceware.org/ml/gdb-patches/2011-04/msg00292.html
> http://sourceware.org/ml/gdb-patches/2011-05/msg00042.html
> commit efa8e67a1ea2d6f90d86efc31076f24e67940f8e
> Author: Thiago Jung Bauermann <bauerman@br.ibm.com>
> Date:   Thu May 5 22:52:09 2011 +0000
>          Demote to sw watchpoint only in update_watchpoint.
>
> Do you really run gdb-7.4+?

$ gdb t
GNU gdb (GDB) 7.4.50.20120710-cvs
Copyright (C) 2012 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-unknown-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /tmp/t...done.
(gdb) l
1       #include <stdio.h>
2
3       int main (void)
4       {
5         int a, b, c;
6
7         a = 5;
8         b = 10;
9         c = b - a;
10        if (c == 5)
(gdb) hb 8
No hardware breakpoint support in the target.
(gdb) b 8
Breakpoint 1 at 0x4004db: file t.c, line 8.
(gdb) quit



-- 
Michael Eager	 eager@eagercon.com
1960 Park Blvd., Palo Alto, CA 94306  650-325-8077