From 1233bcfd63e5cc54b487c2fc91f51aa1b455996f Mon Sep 17 00:00:00 2001
From: Andrew Waterman <andrew@sifive.com>
Date: Fri, 9 Feb 2024 01:54:27 -0800
Subject: [PATCH] Add clarification that misa implications are one-way

---
 src/machine.adoc | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/machine.adoc b/src/machine.adoc
index c8937383d..e7db0c046 100644
--- a/src/machine.adoc
+++ b/src/machine.adoc
@@ -228,6 +228,11 @@ write to `misa` is suppressed, leaving `misa` unchanged.
 When software enables an extension that was previously disabled, then
 all state uniquely associated with that extension is UNSPECIFIED, unless otherwise specified by that extension.
 
+NOTE: Although one of the bits 25--0 in `misa` being set to 1 implies that
+the corresponding feature is implemented, the inverse is not necessarily
+true: one of these bits being clear does not necessarily imply that the
+corresponding feature is absent.
+
 ==== Machine Vendor ID Register `mvendorid`
 
 The `mvendorid` CSR is a 32-bit read-only register providing the JEDEC