embOS MPU on CortexM

embOS is a priority-controlled real-time operating system, designed to be used as foundation for the development of embedded applications.

FAQ

I want use the Cortex-M memory attributes with embOS-MPU Cortex-M

The Cortex-M memory attributes include the following:

Bufferable: Write to memory can be carried out by a write buffer while the processor continues on next instruction execution.

Cacheable: Data obtained from memory read can be copied to a memory cache so that next time it is accessed the value can be obtained from the cache to speed up the program execution.

Sharable: Data in this memory region could be shared by multiple bus masters. Memory system needs to ensure coherency of data between different bus masters in shareable memory region.

TEX: Type Extension field

These bits are implemented in the Cortex-M MPU Region Base Attribute and Size Register (0xE000EDA0):
31:29       Reserved
28          XN            R/W         — Instruction Access Disable (1 = disable instruction fetch from this region; an attempt to do so will result in a memory management fault)
27          Reserved
26:24       AP            R/W         — Data Access Permission field
23:22       Reserved
21:19       TEX           R/W         — Type Extension field
18          S             R/W         — Shareable
17          C             R/W         — Cacheable
16          B             R/W         — Bufferable
15:8        SRD           R/W         — Subregion disable
7:6         Reserved
5:1         REGION SIZE   R/W         — MPU Protection Region size
0           ENABLE        R/W         — Region enable