From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Mon, 30 Apr 2018 07:37:26 +0000 (+0100)
Subject: clarify
X-Git-Tag: convert-csv-opcode-to-binary~5419
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=dd7ca267e17640b72e4b5201927987297615485c;p=libreriscv.git

clarify
---

diff --git a/isa_conflict_resolution/mvendor_march_warl.mdwn b/isa_conflict_resolution/mvendor_march_warl.mdwn
index 32f2a539b..156f72ff0 100644
--- a/isa_conflict_resolution/mvendor_march_warl.mdwn
+++ b/isa_conflict_resolution/mvendor_march_warl.mdwn
@@ -26,6 +26,16 @@ main considerations are:
 * Backwards compatibility.  Is the change zero-impact (for existing systems)
 * Forwards compatibility.  Does the change affect (limit) future hardware?
 
+Note that unlike with MISA, state information is **not permitted to be
+destroyed** during or by a switch-over.  Switch-over to a different
+mvendorid-marchid tuple shall have the effect of *purely* disabling certain
+instruction encodings and enabling others.
+
+Note also that during context-switching *all* state of *all* custom
+extensions (and variants of the Base Standards) are saved onto the stack,
+given that a hart may, at any time, switch between any available
+mvendorid-marchid tuples.
+
 ## Compliance
 
 It was pointed out early in the discussions that Compliance Testing may