IN  struct _LOADER_PARAMETER_BLOCK *LoaderBlock,
  IN  PSTRING NtDeviceName,
  OUT PUCHAR NtSystemPath,
  OUT PSTRING NtSystemPathString

Routine Description:

    This routine assigns DOS drive letters to eligible disk partitions
    and CDROM drives. It also maps the partition containing the NT
    boot path to \SystemRoot. In NT, objects are built for all partition
    types except 0 (unused) and 5 (extended). But drive letters are assigned
    only to recognized partition types (1, 4, 6, 7, e).

    Drive letter assignment is done in several stages:

        1) For each CdRom:
            Determine if sticky letters are assigned and reserve the letter.

        2) For each disk:
            Determine how many primary partitions and which is bootable.
            Determine which partitions already have 'sticky letters'
                and create their symbolic links.
            Create a bit map for each disk that idicates which partitions
                require default drive letter assignments.

        3) For each disk:
            Assign default drive letters for the bootable
                primary partition or the first nonbootable primary partition.

        4) For each disk:
            Assign default drive letters for the partitions in
                extended volumes.

        5) For each disk:
            Assign default drive letters for the remaining (ENHANCED)
                primary partitions.

        6) Assign A: and B: to the first two floppies in the system if they
            exist. Then assign remaining floppies next available drive letters.

        7) Assign drive letters to CdRoms (either sticky or default).


    LoaderBlock - pointer to a loader parameter block.

    NtDeviceName - pointer to the boot device name string used
            to resolve NtSystemPath.

Return Value: