Level 2 Memory System
ARM DDI 0500D
Copyright © 2013-2014 ARM. All rights reserved.
7-14
ID021414
Non-Confidential
In a CHI configured Cortex-A53 processor, there is no fixed mapping between CHI transaction
IDs and cores. Some transaction IDs can be used for either reads or writes.
See the
ARM
®
AMBA
®
5 CHI Protocol Specification
for more information about the CHI signals
described in this manual.
7.4.2
CHI transfers
Table 7-12
shows the CHI transactions that can be generated, and some typical operations that
might cause the transactions to be generated. This is not an exhaustive list of ways to generate
each type of transaction, because there are many possibilities.
Table 7-12 CHI transactions
Transaction
Operation
ReadNoSnp
Non-cacheable loads or instruction fetches. Linefills of non-shareable cache lines into L1 or L2.
ReadOnce
Cacheable loads that are not allocating into the cache, or cacheable instruction fetches when there is no L2
cache.
ReadClean
Not used.
ReadShared
L1 Data linefills started by a load instruction, or L2 linefills started by an instruction fetch.
ReadUnique
L1 Data linefills started by a store instruction.
CleanUnique
Store instructions that hit in the cache but the line is not in a unique coherence state.
MakeUnique
Store instructions of a full cache line of data, that miss in the caches, and are allocating into the L2 cache.
CleanShared
Cache maintenance instructions.
CleanInvalid
Cache maintenance instructions.
MakeInvalid
Cache maintenance instructions.
DVMOp
TLB and instruction cache maintenance instructions.
EOBarrier
DMB instructions.
ECBarrier
DSB instructions. DVM sync snoops received from the interconnect.
WriteNoSnpPtl
Non-cacheable store instructions.
WriteNoSnpFull
Non-cacheable store instructions, or evictions of non-shareable cache lines from the L1 and L2 cache.
WriteUniqueFull
Cacheable writes of a full cache line, that are not allocating into L1 or L2 caches, for example streaming writes.
WriteLineUniquePtl
Cacheable writes of less than a full cache line that are not allocating into L1 or L2.
WriteBackFull
Evictions of dirty lines from the L1 or L2 cache.
WriteBackPtl
Not used.
WriteCleanFull
Evictions of dirty lines from the L2 cache, when the line is still present in an L1 cache. Some cache
maintenance instructions.
WriteCleanPtl
Not used.
WriteEvictFull
Evictions of unique clean lines, when configured in the L2ACTLR.
Evict
Evictions of clean lines, when configured in the L2ACTLR.