Zjpm: Value of N in M-mode

riscv / riscv-j-extension

Working Draft of the RISC-V J Extension Specification

https://jira.riscv.org/browse/RVG-128

Creative Commons Attribution 4.0 International

158 stars 19 forks source link

Zjpm: Value of N in M-mode #33

Closed abrestic-rivos closed 11 months ago

abrestic-rivos commented 1 year ago

For the purposes of determining N, I'm assuming M-mode should be equivalent to the BARE case -- i.e. 16 if Zjpmbare16 is present and 0 otherwise. Can we be explicit about this in the spec?

martinmaas commented 11 months ago

As of the latest version (75e6aa4), Zjpm no longer defines the value of N and instead defines N to be implementation-specific (Section 2.4). Profiles may constrain N for different privilege modes and address translation modes, including Bare and M-mode. As such, if a profile wishes to define that N be the same in both cases, it can do so.