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Re: [PATCH 2/3] Implement new features needed for handling SystemTap probes


>>>>> "Pedro" == Pedro Alves <palves@redhat.com> writes:

Pedro> I don't understand why we'd now skip the test when we don't have
Pedro> the unwinder stap probe,

I think the patch checks for the probe and for the unwinder debug hook,
and bails if they are both missing.

If either one exists then the test should work.

Pedro> This made me wonder about something else with this semaphore
Pedro> handling: the target can itself stop tracing, without GDB requesting
Pedro> it.  E.g., if the trace buffer is full.  If so, then you'll miss
Pedro> decrementing the semaphore count...  Even worse with disconnected
Pedro> tracing; GDB might not even be connected when the tracing stops,
Pedro> and when you reconnect, you have no clue whether to decrement
Pedro> the counts or not...

Leaving the semaphore enabled in corner cases is not terrible.
It may affect performance a little, but that is all.

Anyone affected will already be doing reasonably sophisticated
debugging -- running disconnected trace experiments.  If it is important
they could also just reset the semaphore to 0 manually.

Tom


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