NTSTATUS
HalpGetFullGeometry(
  IN  PDEVICE_OBJECT DeviceObject,
  IN  PDISK_GEOMETRY Geometry,
  OUT PULONGLONG RealSectorCount
  );

Routine Description:

    We need this routine to get the number of cylinders that the disk driver
    thinks is on the drive.  We will need this to calculate CHS values
    when we fill in the partition table entries.

Arguments:

    DeviceObject - The device object describing the entire drive.

    Geometry - The geometry of the drive
    
    RealSectorCount - the actual number of sectors reported by the drive (
                      this may be less than the size computed by the geometry)

Return Value:

    None.