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> + 2 others that I honestly have no idea what they do The original RV32I and RV64I required some control registers for high frequency counters and instruction
by jecel 2y ago
> + 2 others that I honestly have no idea what they do
The original RV32I and RV64I required some control registers for high frequency counters and instruction counters. You also needed the instructions to access these registers. This proved to be too complex for the simplest implementations, so recently (five years ago?) this functionality has been moved to their own extensions.
Including these extensions in G makes the current G have the same functionality as the original G.
- snvzz 2y agoImportant to highlight this happened before the base RISC-V specs were ratified. i.e. features have not been removed after ratification.