Re: [PATCH v3 1/7] Documentation: dynamic-debug: Add description of level bitmask

Joe Perches
2020-06-09T16:58:26Z

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