SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
There are two MMUs. Each of the two EDMA TCs is mapped to a different MMU. One of the MMUs is also shared with ARP32 program and data accesses. The ARP32 program cache and data accesses share an MMU to provide a convenient mechanism whereby ARP32 debug accesses have a single and consistent view of the system, which is equivalent to ARP32 software view. For the EDMA paths, the two MMUs provide maximum concurrency for each TC and its respective accesses to system memory. See Table 8-13 for MMU Configurations
Name | Description | Configuration |
---|---|---|
MMU_Entries_Number | The number of entries in the TLB cache | 32 entries |
MMU_Command_Bypass | Bypass command register | 2 cycle latency |
MMU_Response_Bypass | Bypass response register(depends on clock speed versus technology) | 2 cycle latency |
MMU_LRU_Enable | LRU algorithm for TLB endry replacement | Disabled |
MMU_RRB_Enable | Determines if Generic RRB module is instantiated (Zero only for DSPSS) | Present |
LOG_DATA_WIDTH | data width configuration | 128-bit data bus |
Each MMU allows multiple EVEs to have the same software even when the EVEs are communicating with each other. This can be accomplished by using virtual addresses for each EVE address space. The predominant use of multiple EVEs occurs when adjacent EVEs communicate with each other and send or receive data from adjacent neighbors. In this case, it is suggested that a consistent right neighbor and left neighbor address is defined with MMU for the EVEs. Keeping the right neighbor and left neighbor address the same across different platforms and devices helps with software reuse strategy.
The suggested address mapping for the left neighbor is 0x4100 0000, and for the right neighbor is 0x4200 0000, where the left neighbor for EVEn is EVEn-1 and the right neighbor for EVEn is EVEn+1. For EVE1, the left neighbor is the last EVE implemented in the SoC, and for the last EVE in the SoC, EVE1 is the right neighbor.
For more information about MMU configuration, see Chapter 20, Memory Management Unit .