In a multiprocessor system, the MPIDR provides an additional processor identification mechanism for scheduling purposes, and indicates whether the implementation includes the Multiprocessing Extensions.

Bits	Name	Function
[31]	MPEA	Multiprocessing Extensions Available
[30]	U	Indicates a Uniprocessor system
[29:25]	-	Reserved.
[24]	MT	Indicates whether the lowest level of affinity consists of logical processors that are implemented using a multi-threading type approach.
[23:16]	Aff2	Affinity level 2.
[15:8]	Aff1	Affinity level 1.
[7:0]	Aff0	Affinity level 0.

Consider __get_MPIDR to access this register.