Implement Ziccid (I$ coherence) correctly and cleanly #2117
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The algorithm is as follows: - The ITLB maintains inclusion of the I$ - The same address cannot be in any hart's ITLB if it is in any hart's STLB, and vice versa The effect is that any word that can be stored-to cannot be in any I$. The old scheme (periodically flush I$) was hacky and didn't correctly respect the in-order fetch rule (i.e. fetches are in-order wrt. each other, and so they see ordered stores in order).
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The algorithm is as follows:
The effect is that any word that can be stored-to cannot be in any I$.
The old scheme (periodically flush I$) was hacky and didn't correctly respect the in-order fetch rule (i.e. fetches are in-order wrt. each other, and so they see ordered stores in order).
cc @jerryz123 - this is just a proof of concept for the moment. It is possible to be smarter with the data structures, e.g. build two snoop filters (one global set that remembers all PPNs that might be in any I$, and another global set that remembers all PPNs that might be in any store TLB). If you have any cleverer ideas, LMK.