Re: How does GDB get the function call stack

[Luis Machado <luis.machado@arm.com>]

On 8/16/22 13:48, Andrew Dinn wrote:
> On 16/08/2022 11:16, hilbert wrote:
>> @Andrew Dinn
>> Now I totally understand. Thank you very much for your patience.
> 
> You are very welcome.
> 
>> By the way, when a multithreaded program hits a breakpoint, GDB can use the command: /*thread ID */
>> /**/to switch between threads arbitrarily,  and view the memory and other information of each thread.
>> This is also implemented using ptrace, right?
> I would assume it relies on ptrace to stop all the threads. However, I have almost zero knowledge of how gdb actually controls the inferior process (my knowledge of gdb is exclusively on the gdb-process side of the fence). You will need to find someone else to obtain a definitive answer.

Sorry, for some funny reason (mailing list software/mail server) I'm not getting hilbert's replies. But Andrew provided great answers.

Reading memory is usually done through /proc/<pid>/mem these days, as it is fastest.

Reading registers for each thread is done by ptrace.

> 
> regards,
> 
> 
> Andrew Dinn
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