On 09/01/2025 12:01, Yeoreum Yun wrote:

Hi Suzuki,

...

Is it not better to have separate "configs" for perf and sysfs ? And etmX driver can populate the "running" config, based on the mode specific config. That way, the configs can be updated independently without affecting the running config or the perf one.

That was i've tried but I've accepted Mike's opinion that it's enough to check whether CS_MODE_DISABLED via coresight_get_mode() in *_store().

"the .._store functions in sysfs should use coresight_get_mode() to ensure this is set to CS_MODE_DISABLED before altering the config, which ensures that the trace system is inactive. We don't' really care about reading the config if trace is running."

There are two issues with that :

1. Sprinkling the get_mode call in each sysfs stor function doesn't look good to me.

2. Someone preparing for a sysfs session must not be prevented from doing so just because there is a perf session running.

Suzuki

Thanks.