trouble overriding DSDT

John Baldwin jhb at
Mon Sep 20 08:59:54 PDT 2004

On Monday 20 September 2004 02:19 am, Nate Lawson wrote:
> Marcel Moolenaar wrote:
> > On Sun, Sep 19, 2004 at 02:07:58PM -0700, Nate Lawson wrote:
> >>The right fix I think is to disable SSDT loading if we've overridden the
> >>DSDT.  Bob, what do you think?  Marcel, we should fix this for 5.3R
> >>because it will prevent people from using custom ASL easily.  Another
> >>quick fix would be to put a comment block around the disassembled SSDT
> >>so it is there for inspection but doesn't affect recompilation.
> >
> > Tricky. The advantage of SSDTs is that it allows you to modularize,
> > which means that one may want to be able to override a single SSDT.
> > In that case, overriding the DSDT does not automaticly imply that
> > none of the SSDTs should be loaded.
> >
> > If by default we do load SSDTs when overriding the DSDT (like we happen
> > to do now by coincidence), we should not dump any SSDTs by default in
> > acpidump(8) and vice versa. This also means that we should be able to
> > just dump some SSDT and override just some SSDT.
> >
> > If overriding is acceptable to be an all or nothing approach, then
> > acpidump(8) behaves correctly and we just need to stop loading SSDTs
> > when the DSDT is overridden.
> Overriding is only for debugging or for known-bad machines.  So I think
> it's acceptable for the user to pass a combined/hacked DSDT+SSDT and
> have it override all DSDT/SSDT tables.  This is the way I'd like to
> handle this.
> For now, I think it makes sense to put the SSDT in a comment block in
> acpidump(8) so that recompiling and overriding works properly and the
> SSDT is still available for examining.  We can do the first fix in
> -current but we need something for 5.3.
> Objections?

I think it's a good idea to override all the DSDT+SSDT's when you load a new 
dsdt.  Otherwise it just makes things much more complicated for the user to 
have to know what lives in different SSDT's, etc.  If acpidump continues to 
dump a full table that can then be compiled into a single foo.dsdt that makes 
the user interface a lot simpler and easier to manage.

John Baldwin <jhb at>  <><
"Power Users Use the Power to Serve"  =

More information about the freebsd-acpi mailing list