5.3.18 GetNextHighMonotonicCount()

There are no use cases for this service by a UEFI Driver. It should never be called.

This service is only used by operating systems to manage the upper 32-bits of the 64-bit monotonic counter after the operating system has called ExitBootServices(). An operating system that chooses to use the UEFI provided 64-bit monotonic counter should acquire the value of the 64-bit monotonic counter before ExitBootServices() using the UEFI Boot Service GetNextMonotonicCount(). The operating system can manage the volatile lower 32-bits of the 64-bit monotonic counter on its own. If a 32bit rollover condition occurs, then the operating system can use the UEFI Runtime Service GetNextHighMonotonicCount() to increment the upper 32-bits of the 64-bit monotonic counter. The upper 32-bits are non-volatile and it is the responsibility of the UEFI firmware to guarantee that the upper 32-bits of the 64-bit monotonic counter are preserved across system resets and power cycles.