INT 15 R - Advanced Power Management Spec - CONNECT 16-BIT PROTMODE INTERFACE
        AX = 5302h
        BX = 0000h (device ID of system BIOS)
Return: CF clear if successful
            AX = real-mode segment base address of protected-mode 16-bit code
                segment
            BX = offset of entry point
            CX = real-mode segment base address of protected-mode 16-bit data
                segment
        CF set on error
            AH = error code (05h,06h,09h) (see AX=5300h)
Notes:  the caller must initialize two consecutive descriptors with the
          returned segment base addresses; these descriptors must be valid
          whenever the protected-mode interface is called, and will have
          their limits arbitrarily set to 64K.
        the protected mode interface is invoked by making a far call with the
          same register values as for INT 15; it must be invoked while CPL=0,
          the code segment descriptor must have a DPL of 0, the stack must be
          in a 16-bit segment and have enough room for BIOS use and possible
          interrupts, and the current I/O permission bit map must allow access
          to the I/O ports used for power management.
        functions 00h-03h are not available from protected mode
SeeAlso: AX=5303h,AX=5304h