the definition of ARCACHE[3] is mentioned below. and also it is used in identifying the write back and write through memory type encoding in AXI4.
as this bit is used in memory type encoding , in which cases the below definition will be used. why there are two definitions for the same signal ?
ARCACHE[3] Other Allocate When asserted, the transaction must be looked up in a cache because it could have been allocated in the cache by another transaction, either a write transaction or a transaction from another master. The transaction must also be looked up in a cache if ARCACHE[2] is asserted. When deasserted, if ARCACHE[2] is also deasserted, then the transaction does not need to be looked up in a cache.
could you please clarify ?
Table A4-5 Memory type encoding
ARCACHE[3:0] AWCACHE[3:0] Memory type
0000 0000 Device Non-bufferable
0001 0001 Device Bufferable
0010 0010 Normal Non-cacheable Non-bufferable
0011 0011 Normal Non-cacheable Bufferable
above table has definition for memory types
Table A4-4 ARCACHE bit allocations
ARCACHE[1] Modifiable When asserted, the characteristics of the transaction can be modified and a larger quantity of read data can be fetched than is required. When deasserted the characteristics of the transaction must not be modified.
Thanks for providing clarifications. why there are two definitions mentioned for same signals .in which contexts these are used