VOID
FASTCALL
xHalGetPartialGeometry(
  IN  PDEVICE_OBJECT DeviceObject,
  IN  PULONG ConventionalCylinders,
  IN  PLONGLONG DiskSize
  );

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.

    ConventionalCylinders - Number of cylinders on the drive.

Return Value:

    None.