Re: Architecture extension proposal for ConfigPtr CSR to "Unified RISC-V Discovery Method" config structure


Tim Newsome <tim@...>
 

On Mon, Jun 28, 2021 at 1:54 PM Philipp Tomsich <philipp.tomsich@...> wrote:
I'd also like to require the pointer be 4-byte aligned, meaning software should ignore the low 2 bits. This will give us 2 extra bits should we need them in the future.

That's OK.  The extension would then define the low two bits as "00" and as "Reserved for future standard use".

In consideration of low-end systems that may point into some memory-mapped serial storage, I would rather avoid this.

It’s also going to cause eventual discussions, once the first devices with errata slip through and cause issues with software ghat assumes this constraint to always hold.

Fair enough. We can invent other mechanisms for future use if needed.

Tim

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