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MPAMCFG_CMAX, MPAM Cache Maximum Capacity Partition Configuration Register

The MPAMCFG_CMAX characteristics are:


The MPAMCFG_CMAX is a 32-bit read-write register that controls the maximum fraction of the cache capacity that the PARTID selected by MPAMCFG_PART_SEL is permitted to allocate. MPAMCFG_CMAX_s controls cache maximum capacity for the Secure PARTID selected by the Secure instance of MPAMCFG_PART_SEL. MPAMCFG_CMAX_ns controls the cache maximum capacity for the Non-secure PARTID selected by the Non-secure instance of MPAMCFG_PART_SEL.



This register is present only when MPAMF_IDR.HAS_CCAP_PART == 1. Otherwise, direct accesses to MPAMCFG_CMAX are RES0.


MPAMCFG_CMAX is a 32-bit register.

Field descriptions

The MPAMCFG_CMAX bit assignments are:


Bits [31:16]

Reserved, RES0.

CMAX, bits [15:0]

Maximum cache capacity usage in fixed-point fraction format by the partition selected by MPAMCFG_PART_SEL. The fraction represents the portion of the total cache capacity that the PARTID is permitted to allocate.

The implemented width of the fixed-point fraction is given in MPAMF_CCAP_IDR.CMAX_WD. Unimplemented bits within the field are RAZ/WI. The implemented bits of the CMAX field are always the most-significant bits of the field.

The fixed-point fraction CMAX is less than 1. The implied binary point is between bits 15 and 16. This representation has as the largest fraction of the cache that can be represented in an implementation with w implemented bits is 1 - 1/w.

Accessing the MPAMCFG_CMAX

This register is within the MPAM feature page memory frames. In a system that supports Secure and Non-secure memory maps, there must be both Secure and Non-secure MPAM feature pages.

MPAMCFG_CMAX_s must be accessible from the Secure MPAM feature page. MPAMCFG_CMAX_ns must be accessible from the Non-secure MPAM feature page.

MPAMCFG_CMAX_s and MPAMCFG_CMAX_ns must be separate registers. The Secure instance (MPAMCFG_CMAX_s) accesses the cache capacity partitioning used for Secure PARTIDs, and the Non-secure instance (MPAMCFG_CMAX_ns) accesses the cache capacity partitioning used for Non-secure PARTIDs.

MPAMCFG_CMAX can be accessed through the memory-mapped interfaces:


Accesses on this interface are RW.


Accesses on this interface are RW.

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