On Sun, 13 Sept 2026 at 19:31, Gilles Grimaud <[email protected]> wrote: > > Hi Peter, > > Thanks, you are right. The v3 change incorrectly treated nPRIV as uniform > across all M-profile CPUs. > > For v4 I will add a dedicated ARM_FEATURE bit for the optional > Unprivileged/Privileged Extension. Cortex-M0 will leave it clear, while the > Cortex-M0+ configuration used by the RP2040 will enable it. Writes to nPRIV > will then be permitted when either the Main Extension or this new feature is > present.
I would suggest making ARM_FEATURE_M_MAIN imply ARM_FEATURE_M_NPRIV (or whatever we calli it) -- see arm_cpu_propagate_feature_implications() where we do that sort of thing. That way we don't have to check both feature bits. thanks -- PMM
