B1.27 CTR, Cache Type Register

The CTR provides information about the architecture of the caches.

Bit field descriptions

CTR is a 32-bit register, and is part of the Identification registers functional group.

This register is Read Only.

Figure B1-23 CTR bit assignments
To view this graphic, your browser must support the SVG format. Either install a browser with native support, or install an appropriate plugin such as Adobe SVG Viewer.


RES1, [31]
RES1Reserved.
RES0, [30:28]
RES0Reserved.
CWG, [27:24]

Cache Write-Back granule. Log2 of the number of words of the maximum size of memory that can be overwritten as a result of the eviction of a cache entry that has had a memory location in it modified:

0b0100Cache Write-Back granule size is 16 words.
ERG, [23:20]

Exclusives Reservation Granule. Log2 of the number of words of the maximum size of the reservation granule that has been implemented for the Load-Exclusive and Store-Exclusive instructions:

0b0100Exclusive reservation granule size is 16 words.
DminLine, [19:16]

Log2 of the number of words in the smallest cache line of all the data and unified caches that the core controls:

0b0100Smallest data cache line size is 16 words.
L1Ip, [15:14]

Instruction cache policy. Indicates the indexing and tagging policy for the L1 Instruction cache:

0b10Virtually Indexed Physically Tagged (VIPT).
RES0, [13:4]
RES0Reserved.
IminLine, [3:0]

Log2 of the number of words in the smallest cache line of all the instruction caches that the core controls.

0b0100Smallest instruction cache line size is 16 words.
Configurations

CTR is architecturally mapped to AArch64 register CTR_EL0. See B2.37 CTR_EL0, Cache Type Register, EL0.

There is one copy of this register that is used in both Secure and Non-secure states.

Bit fields and details not provided in this description are architecturally defined. See the Arm® Architecture Reference Manual Armv8, for Armv8-A architecture profile.

Non-ConfidentialPDF file icon PDF version100442_0200_00_en
Copyright © 2016–2018 Arm Limited or its affiliates. All rights reserved.