On Tue, 2020-06-09 at 13:16 +0200, Greg Kroah-Hartman wrote:

What is wrong with the existing control of dynamic
debug messages that you want to add another type of arbitrary grouping
to it? 

There is no existing grouping mechanism.

Many drivers and some subsystems used an internal one
before dynamic debug.

$ git grep "MODULE_PARM.*\bdebug\b"|wc -l
501

This is an attempt to unify those homebrew mechanisms.

Stanimir attempted to add one for his driver via a
driver specific standardized format substring for level.

And who defines that grouping?

Individual driver authors

Will it be driver/subsystem/arch/author specific?  Or kernel-wide?

driver specific

This feels like it could easily get out of hand really quickly.

Likely not.  A question might be how useful all these
old debugging printks are today and if it's reasonable
to just delete them.

Why not just use tracepoints if you really want to be fine-grained?

Weight and lack of class/group capability