Re: how to create and hardware watchpoint from a commands list.

[Julien Chavanton <jchavanton@gmail.com>]

Hi Doug, thank you for trying to help, I spent a few hours on this so
I am interested to solve this puzzle for next time.

----------------------------
By doing it manually I mean,

step-1) I type :

printf "0x%x\n", &call->stream->session->ext.settings.mode

and then :

step-2) I type :
watch *(int *){result from step 1}

-------------------------------
This did not work for me :

watch -location call->stream->session->ext.settings.mode
-------------------------------

I can rerun the session and provide exact output or I could just try
an alternative "piping" the output of step-1 to step-2 from the GDB
"command line interpreter" not sure how it is called, this as to be
executed from a breakpoint command list ?


On Sun, Feb 8, 2015 at 5:26 AM, Doug Evans <xdje42@gmail.com> wrote:
> On Wed, Feb 4, 2015 at 2:14 AM, Julien Chavanton <jchavanton@gmail.com> wrote:
>> Hi Folks, I would like to create and hardware watchpoint from a commands list.
>>
>> retrieve the addres of a variable and create a watch.
>>
>> watch *(int *) &call->stream->session->ext.settings.mode
>>
>> Manualy this is working fine, but I do not know the right syntax in GDB.
>
> What do you mean by this working manually but then not knowing the right syntax?
>
>>
>> I tried "watch -location call->stream->session->ext.settings.mode"
>>
>> And sereval other things, is there a way to pipe the output of one
>> command to another one ?
>
> You tried several things, but you need to be more specific about
> what problems you had.  Complete unedited session logs are useful.
>
> There are various ways to "pipe" (for lack of a better term) the
> output of previous commands into subsequent commands.
> value history, convenience variables and/or eval or python come to mind.
> But do you need to?
> What about "watch -location ..." didn't work?
>
>>
>> watch *(int *) | printf "0x%x\n", &call->stream->session->ext.settings.mode
>>
>>
>> ----------------------------------------------------------
>>
>>
>> define myhook
>>   echo myhook \n
>>   next
>>   next
>>   next
>>   print call->stream->session->ext.settings.mode
>>   print &call->stream->session->ext.settings.mode
>>   printf "watch *(int *)0x%x\n", &call->stream->session->ext.settings.mode
>> end
>>
>> break set_settings
>> commands
>>  myhook
>> end