* GDB breakpoint implementation for multithreaded programms
@ 2014-05-10 22:00 Sofia
2014-05-11 3:27 ` Luis Machado
0 siblings, 1 reply; 2+ messages in thread
From: Sofia @ 2014-05-10 22:00 UTC (permalink / raw)
To: gdb
I'm writing my GDB stub and trying to set breakpoints on different threads.
When I don't ask GDB about the number of threads, It works fine as a single-
threaded application and breakpoints are set correctly. But when I enter -
'info threads', something strange happens.
Firstly, GDB reads the contents of all threads' registers(it's OK). Then I
enter 'continue' and see that breakpoints are not set at all threads my
program has. I don't understand why, but the packet Z0(breakpoint packet) is
only sent to inactive thread. The documentation says that if the thread id is
not specified, breakpoints will be set at all threads. What's wrong with this
or where can I read about such GDB behavior?
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: GDB breakpoint implementation for multithreaded programms
2014-05-10 22:00 GDB breakpoint implementation for multithreaded programms Sofia
@ 2014-05-11 3:27 ` Luis Machado
0 siblings, 0 replies; 2+ messages in thread
From: Luis Machado @ 2014-05-11 3:27 UTC (permalink / raw)
To: Sofia, gdb
On 05/10/2014 06:56 PM, Sofia wrote:
> I'm writing my GDB stub and trying to set breakpoints on different threads.
> When I don't ask GDB about the number of threads, It works fine as a single-
> threaded application and breakpoints are set correctly. But when I enter -
> 'info threads', something strange happens.
>
> Firstly, GDB reads the contents of all threads' registers(it's OK). Then I
> enter 'continue' and see that breakpoints are not set at all threads my
> program has. I don't understand why, but the packet Z0(breakpoint packet) is
> only sent to inactive thread. The documentation says that if the thread id is
> not specified, breakpoints will be set at all threads. What's wrong with this
> or where can I read about such GDB behavior?
>
>
>
Is this a software breakpoint (Z0/z0) or a hardware breakpoint we are
talking about?
A software breakpoint should be valid for all threads if the threads are
executing a shared piece of code. If these breakpoints are not
triggering, we may have a bug somewhere.
For hardware breakpoints, the target code (in this case, the remote
stub) is responsible for replicating the hardware breakpoint settings
(register contents) to all threads upon their creation.
What version of GDB are you using?
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