Re: Fast-track extension proposal for "Sv32 Svnapot and Svpbmt"
On Tue, Jul 26, 2022 at 6:38 PM Guo Ren <guoren@...> wrote:
> My earlier comments were wrt PBMTE=0 and that these bits are not ignored but instead cause a Page Fault. Or did I miss that your proposal defines that bits [30:29] go back to being normal PA bits (and not reserved bits as in RV64)? In which case these bits are still not ignored.
In the current arch, the 'N' bit exists only as a function of whether the Svnapot extension is implemented or not. Otherwise it is a Reserved bit. And all this is orthogonal to bits [30:29] and whether Svpbmt is implemented or not.
Unless there is a good justifying reason to do differently in your RV32 proposal, bit  and bits [30:29] should not be mixed together in any manner. Their arch behaviors are orthogonal to and independent of each other.