Determining if write combining is enabled from user mode

Hi all. In HalQuerySystemInformation I can determine if write combining is enabled.

Does anyone know of an existing interface to get this information from user mode, or would this have to come through some driver interface from KM?

Hum, I notice now that this Hal function is no longer documented. Anyone know the currently approved method of checking for write combining? It looks like most display drivers have a checkbox for this, so they must have a way to figure this out.

Thanks,
Loren