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riscv / riscv-bitmanip

Working draft of the proposed RISC-V Bitmanipulation extension
https://jira.riscv.org/browse/RVG-122
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Does MISA.B control zba/zbb/zbc/zbs? #183

Closed jrahmeh closed 1 year ago

jrahmeh commented 1 year ago

We are implementing the bit-manipulation extension, do we then implement the B bit in the MISA CSR? The privileged spec says that the B bit is reserved and must return zero on read.

pdonahue-ventana commented 1 year ago

No. misa.B was previously going to be used for the B extension but it is now (in the ratified priv spec) a reserved bit. There is no B extension, just a group of Zb* extensions which are not related to the B bit.

jrahmeh commented 1 year ago

Thanks for the quick reply. Closing.