Memory Defragmentation; Dsp Memory Management Unit - Texas Instruments OMAP5910 Reference Manual

6

DSP Memory Management Unit

6.1 Overview
6.1.1 Purpose of the MMU
Figure 21.

Memory Defragmentation

SPRU890A
DSP core and DSP DMA accesses to DSP external memory are handled by
the DSP external memory interface (EMIF) in conjunction with the DSP
Memory Management Unit (MMU). The DSP MMU maps external memory
requests to the OMAP physical address space. The MMU also provides fault
and permission checking, and performs endianess conversion. It is configured
by the MPU core. Section 10 describes MMU endianess.
The use of an MMU offers two major benefits:
Memory defragmentation: Fragmented physical memory can be
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translated into continuous virtual memory without moving any data.
Task protection: Illegal, non-allowed accesses to memory locations can be
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detected and prevented.
Figure 21 and Figure 22 illustrate the benefits of using an MMU.
Virtual memory
Memory region 1
Memory region 2
In Figure 21, memory region 1 and memory region 2 are fragmented in
physical memory. Using the MMU, they can be translated to appear as one
contiguous memory region in the virtual memory space.
DSP Memory Management Unit
Physical memory
Memory region 1
Memory region 2
DSP Subsystem 65