6.4.2. ACE transactions

Table 6.1 shows the ACE transactions that each type of memory access generates .

Table 6.1. ACE transactions

Attributes ACE transaction
Memory typeShareabilityDomainLoadStoreLoad exclusiveStore exclusive
Strongly Ordered-SystemReadNoSnoopWriteNoSnoop

ReadNoSnoop and ARLOCK[0] set to 1

WriteNoSnoop and AWLOCK[0] set to 1

Device-
Normal, inner Non-cacheable, outer Non-cacheableNon-shared SystemReadNoSnoopWriteNoSnoop

ReadNoSnoop and ARLOCK[0] set to 1

WriteNoSnoop and AWLOCK[0] set to 1
Inner-shared
Outer-shared
Normal, inner Non-cacheable, outer Write-Back or Write-Through, or Normal, inner Write-Through, outer Write-Back, Write-Through or Non-cacheableNon-shared Non-shareableReadNoSnoopWriteNoSnoop

ReadNoSnoop and ARLOCK[0] set to 0

WriteNoSnoop and AWLOCK[0] set to 0

Inner-sharedInner shareableReadOnceCleanUnique followed by Write-BackReadClean with ARLOCK[0] set to 1[a]CleanUnique with ARLOCK[0] set to 1 followed by Write-Back[a]
Outer-sharedOuter shareable
Normal, inner Write-Back, outer Non-cacheable, Write-Through, or Write-BackNon-shared Non-shareableReadNoSnoopWriteNoSnoop

ReadNoSnoop and ARLOCK[0] set to 0

WriteNoSnoopand AWLOCK[0] set to 0

Inner-sharedInner ShareableReadSharedCleanUnique if required, then a Write-Back when the line is evictedReadShared with ARLOCK[0] set to 1[a]CleanUnique with ARLOCK[0] set to 1 if required, then a Write-Back when the line is evicted[a]
Outer-sharedOuter Shareable

[a] For Inner Shareable transactions where BROADCASTINNER is set to 0, ARLOCK[0], is set to 0. For Outer Shareable transactions where BROADCASTOUTER is set to 0, ARLOCK[0], is set to 0.


See the AMBA AXI and ACE Protocol Specification for more information about ACE transactions.

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