Read the seed CSR

Paul Ku


Maybe the little issue has been solved. I am just curious. The follows come from "4.1. The seed CSR" in Cryptography Extensions Volume I. It talks about the side effect on read the seed CSR.

4.1. The seed CSR
For security reasons, the interface guarantees that secret entropy words are not made available multiple times. Hence polling (reading) must also have the side effect of clearing (wipe-on-read) the entropy contents and changing the state to WAIT (unless there is entropy immediately available for ES16). Other states (BIST, WAIT, and DEAD) may be unaffected by polling.

However, in the introduction of Chapter 2 in the privileged spec (20211203), it says, "Standard CSRs do not have side effects on reads but may have side effects on writes."

Is there any explanation? or we should modify one of them?