The ACPI driver is not required yet, but some stubs have already been
added to the sources; only to test the driver initialization function
of the driver manager.
In the GDT, the direction in which the stack grows in x86 has been
ignored; for reserving space on the stack, the ESP register was added
to and for cleaning up that space, ESP was subtracted from. That is
obviously wrong and is fixed with this commit.
The newly added function only searchs the "RSD PTR "-signature in the
Main BIOS Area, not in the *Extended* BIOS Area. That should be fixed,
but right now, it's of little relevance.