The challenge (!) is that RTWN_DEBUG is enabled by default in the rtwn module builds, rather than the module pulling in opt_rtwn.h from the build environment / kernel configuration directory. That's why I made it a different option.

For ath(4) it's behind ATH_DIAGAPI.

I sometimes forget that not everything is being enforced by iommu / newbus accessor range checking. Lemme cap it at 64k for now

The add a /* #define RTWN_DEBUG_REGIO */ at the top of the file and he (you) who needs can change it there and enable it; it doesn't have to be exposed to the build environment.
Like is done for so many DPRINTF cases (and similar) in lots of drivers in sys/dev/

It's easy to make the module pull it in from the kernel as well as having a stand alone default. It's what we do normally for other modules. Should i delve so i can make a detsiled suggestion?

It's easy to make the module pull it in from the kernel as well as having a stand alone default. It's what we do normally for other modules. Should i delve so i can make a detsiled suggestion?

Yeah, we should really fix it to do the right thing.

For now i'll stick this under RTWN_DEBUG; we can add the other option later when we've cleaned up the module opt_rtwn.h generation and such.