This option enables support for the ACPI-WMI driver core.

The ACPI-WMI interface is a proprietary extension of ACPI allowing
the platform firmware to expose WMI (Windows Management Instrumentation)
objects used for managing various aspects of the underlying system.
Mapping between ACPI control methods and WMI objects happens through
special mapper devices (PNP0C14) defined inside the ACPI tables.

Enabling this option is necessary for building the vendor specific
ACPI-WMI client drivers for Acer, Dell an HP machines (among others).

It is safe to enable this option even for machines that do not contain
any ACPI-WMI mapper devices at all.

source code:

drivers/platform/wmi/