Re: Can GDB support "temporal breakpoints"?

[joaoandreferro@sapo.pt]

Citando Doug Evans <dje@google.com>:

> On Wed, Oct 29, 2014 at 11:55 AM,  <joaoandreferro@sapo.pt> wrote:
>> Hello everyone, again,
>>
>> From what I've learned after reading GDB's excellent documentation, I know I
>> can set a memory trigger (i. e., a breakpoint that is set every time a
>> certain memory address changes) by setting a watchpoint at the desired
>> memory address (a practical example is available here:
>> http://stackoverflow.com/questions/58851/can-i-set-a-breakpoint-on-memory-access-in-gdb).
>> The question I have now is if I can set a temporal breakpoint (i. e., a
>> breakpoint that is only triggered after a user-defined amount of time has
>> passed), in few words a breakpoint that is only fired after some kind of
>> timer has expired. I haven't found anything related to this on the GDB docs,
>> so I guess it's not possible, but they are huge and maybe I've missed
>> something, somewhere. If anyone can confirm or deny this deduction, it would
>> be great, because this feature is crucial to my work.
>
> Hi.
>
> There is no such thing, per se, but you might be able to approximate it
> by a breakpoint on a line of code that only triggers when the time  
> has passed,
> or after the breakpoint is hit a certain number of times.

Hi Doug, thanks for your answer.

I know how I can set a breakpoint that only triggers after being hit a  
certain number of times, but how I'd be able to set a breakpoint on a  
line of code that only triggers after a certain time has passed? E.  
g., are you referring about writng a little piece of code (in C, for  
instance) executing something only after a timer manually set by  
myself, in that same code? If that's it, in that case I don't know if  
it will be possible, because I'm also using KGDB, and so I want the  
lowest intrusion possible.

>
> I can also imagine a hack where you run a side program
> that sleeps for the specified period of time and it sends SIGUSR1
> (or whatever) to the inferior, and then have gdb catch SIGUSR1,
> do whatever you want at that time,
> and then resume the inferior (discarding the signal).

I'll investigate this solution, although I think I'll have the sma  
intrusion problem (in the Linux kernel).

Thanks!