i have done few testing and i noticed that :
1. when you set an hardware break point to address XXXXX
and you do something like :
int * ptr = XXXXX;
*ptr = 9;
this will work .
2. when you set an hardware break point to address XXXXX
int *ptr = XXXXX -4;
*(ptr + 4) =9;
didnt work.
jidong xiao wrote:
> On Fri, May 23, 2008 at 1:38 PM, Avi Nehori <[EMAIL PROTECTED]> wrote:
>
>> yes ,you are correct :)
>> seems like the debug registers are being set correctly(i have checked it and
>> debugged it ),but still the breakpoint does not
>> break....
>> i have done a special testing ,i can tell you that if you will write the
>> memory address directly --- it will break.
>> but if you write the memory address indirectly ---- it will not break !!!
>>
> What do you mean by "write the memory address indirectly"?
>
> Regards
> Jason
>
>
>>
>> Jay Lan wrote:
>>
>>> Avi Nehori wrote:
>>>
>>>
>>>> Jay,
>>>> try to set an hardware breakpoint to a global variable and then modify
>>>> it .
>>>> the system will not drop into kdb in this case.
>>>>
>>>>
>>> Hi Avi,
>>>
>>> I reprodued the problem. KDB hardware breakpoint is triggered on
>>> access to a function, but not on value changes to a global variable.
>>> It would be nice, isn't it? Hmmm...
>>>
>>> - jay
>>>
>>>
>>>
>>>> Jay Lan wrote:
>>>>
>>>>
>>>>> Avi Nehori wrote:
>>>>>
>>>>>
>>>>>> Jay,
>>>>>> the patch didnt work for me.
>>>>>> I'm still looking for a resolution...
>>>>>>
>>>>>>
>>>>> Hmmm, i just tested with Konstantin's patch on 2.6.25 and
>>>>> 2.6.26-rc3, and it seemed to work for me.
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>> Entering kdb (current=0xf7841c80, pid 0) on processor 1 due to Keyboard
>>>>>> Entry
>>>>>>
>>>>>>
>>>>> [1]kdb> bpha do_sync
>>>>> Forced Instruction(Register) BP #0 at 0xc017b6a4 (do_sync)
>>>>> is enabled in dr0 globally
>>>>> [1]kdb> go
>>>>>
>>>>> I set up a global hardware breakpoint at do_sync here.
>>>>> Then i entered 'sync' command from a shell. The system dropped into KDB:
>>>>>
>>>>> Instruction(Register) breakpoint #0 at 0xc017b6a4
>>>>> 0xc017b6a4 do_sync: push %ebx
>>>>>
>>>>> Entering kdb (0xf72a23a0, pid 5473) on processor 2 due to Debug @
>>>>> 0xc017b6a4
>>>>> [2]kdb>
>>>>>
>>>>> You are testing a 2.4.21 kernel... I do not know if KDB support i386
>>>>> in 2.4.21 at all.
>>>>>
>>>>> Keith Owens did a tremendous job in making KDB backtrace working on
>>>>> x86_64/i386 and fixed other bugs along the way, but his work did not
>>>>> complete until 2.6.23. My brief effort of back porting the x86_64/i386
>>>>> KDB support to sles10sp2 (2.6.16 based) and rhel5.2 (2.6.18 based)
>>>>> did not work well. So, honestly, i recommand you move up to 2.6.23
>>>>> or later.
>>>>>
>>>>> Thanks,
>>>>> - jay
>>>>>
>>>>>
>>>>>
>>>>>> Jay Lan wrote:
>>>>>>
>>>>>>
>>>>>>> Hi Avi,
>>>>>>>
>>>>>>> Did Konstantin's patch work for you? His patch caused ia64
>>>>>>> compilation to fail, but i would like to know if his patch
>>>>>>> work for you on i386.
>>>>>>>
>>>>>>> Thanks!
>>>>>>>
>>>>>>> - jay
>>>>>>>
>>>>>>>
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