Architectures and Processors forum Can I map the code/data memory as device memory

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Can I map the code/data memory as device memory

allen.zhang over 7 years ago

For example, map the EL3 firmware memory as device memory, What we should concern? Thanks!

+1 Peter Rielly over 7 years ago

Hi,

The architecture doesn't allow code to be executed out of device memory so that would be a concern. If you only mean data pages then there is no particular reason this won't work, although it will be slow.

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0 allen.zhang over 7 years ago in reply to Peter Rielly

Thanks.

We have to run program as normal memory and IO range as device memory?
What about set the RO/RW/IO range as uncacheable memroy?
What about close MMU to run the el3 firmware?
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0 Peter Rielly over 7 years ago in reply to allen.zhang

Hi,

IO memory needs to be uncached but Device memory is always uncached so that is cool.

Instructions must be in Normal memory, which can be cached or uncached.

@EL3 with the MMU off *all* data accesses will be to Device memory and *all* instruction fetches will be to Normal memory. The address range doesn't matter.
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