Hi there, I am working on providing memory protection for many targets/BSPs that RTEMS support through a library called libmm. Previous MMU projects depended on "Pages" to provide memory protection. I was thinking of using BATs for extending libmm for PowerPC targets. The following are some characteristics for BAT (Block Address Translation) and Pages for PowerPC/mpc6xx.
For BATs : - BAT sizes varies from 128KB up to 256 MB. - 8 pairs of register to describe blocks of memory: 4 for data blocks and 4 for instructions blocks. - It's faster than Page translation. - Simple. For Pages : - Page sizes begins from 4KB. - Hash function are used for Page tables search and insert. - Slower than BAT. - Complex Code and cost much time when dynamically change attributes. The current code for libmm/PowerPC is using Pages. Do you think it's suitable to implement libmm to use BAT also ? Waiting for your feed back. Thanks, Hesham
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