ACPI runtime debugging

[Jukka Ruohonen <jruohonen%iki.fi@localhost>]

Hello.

The included files enable some runtime debugging options for ACPI. In a
nutshell: if the kernel has been compiled with ACPI_DEBUG, there are two new
sysctl(7) variables that control the debug output from (and via) ACPICA.

The rationale is:

        1. This helps to debug ACPI (duh). While there is the actual
           debugger and also some user space utilities exist, this makes
           conventional "printf-debugging" a lot easier as the whole deal
           (parsing, evaluation, traces, etc.) is available with a single
           switch. If one has to debug ACPI for someone else, this
           information can also be more useful, at least when compared to
           the daunting task of reading the DSDTs.

        2. We have already added the _COMPONENT definitions to most of the
           ACPI device drivers, so we might as well utilize the full benefit
           from these.

        3. An indirect benefit is that the "#ifdef ACPI_DRIVER" clauses
           could be eliminated from the ACPI subtree. Adding more "trace
           points" would also become easier.

In terms of code, the patch is small and simple.

- Jukka.

* * *

Code:

        ftp://ftp.NetBSD.org/pub/NetBSD/misc/jruoho/acpi_debug.c

Documentation and a required small diff:

        ftp://ftp.NetBSD.org/pub/NetBSD/misc/jruoho/acpi_debug.diff