Table A9-4 ACE transactions (continued)
Attributes
ACE transaction
Memory type
Shareability Domain
Load
Store
Load exclusive
Store exclusive
Normal, inner Non-
cacheable, outer Write-
Back or Write-
Through, or Normal,
inner Write-Through,
outer Write-Back,
Write-Through or Non-
cacheable, or Normal
inner Write-Back outer
Non-cacheable or
Write-Through
Non-shared
System
ReadNoSnoop WriteNoSnoop
ReadNoSnoop
ReadNoSnoop
Inner-shared
System
ReadNoSnoop WriteNoSnoop
ReadNoSnoop with
ARLOCKM
set to
HIGH
WriteNoSnoop with
ARLOCKM
set to
HIGH
Outer-shared
System
Normal, inner Write-
Back, outer Write-
Back
Non-shared
Non-
shareable
ReadNoSnoop WriteNoSnoop
ReadNoSnoop
WriteNoSnoop
Inner-shared
Inner
Shareable
ReadShared
ReadUnique or
CleanUnique if
required, then a
WriteBack when
the line is evicted
ReadShared with
ARLOCKM
set to
HIGH
CleanUnique with
ARLOCKM
set to
HIGH if required,
then a WriteBack
when the line is
evicted
Outer-shared
Outer
Shareable
The following table shows the ACE 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 A9-5 ACE transactions and typical operations
Transaction
Operation
ReadNoSnoop
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.
ReadNotSharedDirty 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. Store instructions that are
not allocating into the L1 or L2 caches, for example when streaming writes.
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.
DVM
TLB and instruction cache maintenance instructions.
DVM complete
DVM sync snoops received from the interconnect.
A9 ACE Master Interface
A9.4 ACE transactions
100236_0100_00_en
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