Re: [PATCH v3 4/8] coresight: tmc-etr: Prevent per-thread events from sharing a sink

[Leo Yan]

On Tue, Jul 28, 2026 at 04:00:16PM +0100, James Clark wrote:

[...]

> The identity and compatibility of a session are determined by the owning
> process, the target process, and the inheritance settings together.

Could you elaborate a bit on the session model you are trying to support
here?

My understanding of a legacy sink such as ETR/ETF is that it can be
owned by only one perf session at a time. Multiple events belonging to
that session may use the sink, but an attempt from another perf session
should be rejected with -EBUSY.

For per-thread mode, I wonder if we could support _only_ non-inherited
events. In that case, we would not need to determine compatibility based
on the target process and inheritance settings.

>From the patch, it seems trying to support a more flexible model, where
an already active legacy sink can also be shared by another perf session
and also support inherit mode for child events?

Thanks,
Leo