Level 2 Memory System
ARM DDI 0500D
Copyright © 2013-2014 ARM. All rights reserved.
7-7
ID021414
Non-Confidential
Table 7-6
shows the encodings for
AWIDM[4:0]
Write ID width
5
The ID encodes the source of the memory transaction. See
Table 7-6
.
Read ID
capability
8n + 4m + 1
8 for each core in the cluster in addition to:
•
4 for the ACP.
•
1 for barriers.
Only Device memory types with nGnRnE or nGnRE can have more than one outstanding
transaction with the same AXI ID. All other memory types use a unique AXI ID for every
outstanding transaction.
Two part DVMs use the same ID for both parts, and therefore can have two outstanding
transactions on the same ID.
Read ID width
6
The ID encodes the source of the memory transaction. See
Table 7-7 on page 7-8
.
a. n is the number of cores.
m is 1 if the processor is configured with an ACP interface, and 0 otherwise.
Table 7-5 ACE master interface attributes (continued)
Attribute
Value
a
Comments
Table 7-6 Encodings for AWIDM[4:0]
Attribute
Value
Issuing capability
per ID
Comments
Write ID
0b000nn
a
1
Core nn system domain store exclusive
0b001nn
a
1
Core nn barrier
0b01000
0
Unused
0b01001
1
SCU generated barrier
0b0101x
0
Unused
0b011nn
a
15
Core nn non-re-orderable device write
0b1xxxx
1
Write to normal memory, or re-orderable device memory
a. Where nn is the core number
0b00
,
0b01
,
0b10
, or
0b11
.