6.4.7 Exclusive access checks

This section describes the exclusive access checks performed by the protocol checker.

Table 6-8 Exclusive access checks performed by the protocol checker

Bus types Description of check AMBA® APB Protocol Specification AMBA 3 AHB-Lite Protocol Specification AMBA 4 AXI and ACE Protocol Specification
APB, AXI4-Lite A transaction cannot be exclusive or locked. Section 2.1 AMBA® APB signals - Section B1.1.1 AXI4 signals not supported in AXI4-Lite
AHB A transaction cannot be exclusive. - Section 2.2 Master signals -
AXI3 A transaction cannot be exclusive and locked. - - Section A7.4 Atomic access signaling
AXI3 Recommended that locked transactions are only used to support legacy devices. - - Section A7.4.1 Legacy considerations
AXI4, ACE-Lite Locked accesses are not supported. - - Section A7.3 Locked accesses
AXI3, AXI4, ACE-Lite The maximum number of bytes that can be transferred in an exclusive burst is 128. - - Section A7.2.4 Exclusive access restrictions
AXI3, AXI4, ACE-Lite The number of bytes transferred in an exclusive access burst must be a power of 2. - - Section A7.2.4 Exclusive access restrictions
AXI4 The burst length for an exclusive access must not exceed 16 transfers. - - Section A7.2.4 Exclusive access restrictions
AXI3, AXI4, ACE-Lite The address of an exclusive transaction is aligned to the total number of bytes in the transaction. - - Section A7.2.4 Exclusive access restrictions
AXI3, AXI4, ACE-Lite Recommended that every exclusive write has an earlier outstanding exclusive read with the same ID. - - Section A7.2.4 Exclusive access restrictions
AXI3, AXI4, ACE-Lite Recommended that the address, size and length of an exclusive write with a given ID is the same as the address, size and length of the preceding exclusive read with the same ID. - - Section A7.2.4 Exclusive access restrictions
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