From ca838c12b0bf61824e62eba60050a4dbc2604698 Mon Sep 17 00:00:00 2001 From: Andrew Waterman Date: Mon, 24 Sep 2018 16:24:48 -0700 Subject: SFENCE behavior is independent of privilege mode --- src/machine.tex | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/src/machine.tex b/src/machine.tex index ba1e1aa..438f75a 100644 --- a/src/machine.tex +++ b/src/machine.tex @@ -2981,9 +2981,7 @@ that affects either the physical memory that holds the page tables or the physical memory to which the page tables point, M-mode software must synchronize the PMP settings with the virtual memory system. This is accomplished by executing an SFENCE.VMA instruction with {\em rs1}={\tt x0} -and {\em rs2}={\tt x0}, after the PMP CSRs are written. Note, SFENCE.VMA is -only guaranteed to synchronize the PMP settings with the virtual memory system -when it is executed in M-mode. +and {\em rs2}={\tt x0}, after the PMP CSRs are written. If page-based virtual memory is not implemented, or when it is disabled, memory accesses check the PMP settings synchronously, so no fence is needed. -- cgit v1.1