Compatibility: EMS 4.0+
Expects: AX    5c00H
Returns: AH    EMM status (0=successful)
Info: This is designed for use by operating systems only and may be
disabled at any time.

This fn warns the EMM that the system is about to reboot.  A very
few hardware-based EMS implementations can maintain valid data
across a warm boot.

See INT 67H 52xxH (get/set handle attribute).

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INT 67H 5c00H: Prepare for Warm Boot