From a7c963a8f195e0335990534c3095c8161f782020 Mon Sep 17 00:00:00 2001 From: lkcl Date: Wed, 12 Jun 2019 15:57:45 +0100 Subject: [PATCH] --- isa_conflict_resolution/isamux_isans.mdwn | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/isa_conflict_resolution/isamux_isans.mdwn b/isa_conflict_resolution/isamux_isans.mdwn index 766cee3a0..5376401c1 100644 --- a/isa_conflict_resolution/isamux_isans.mdwn +++ b/isa_conflict_resolution/isamux_isans.mdwn @@ -33,6 +33,14 @@ thus, the need for having a per-privilege per-permutation utvec/stvec/htvec. # Why ISAMUX / ISANS has to be WLRL and mandatory trap on illegal writes +The namespaces, set by bits in the CSR, are functionally directly equivalent to c++ nanespaces, even down to the use of braces. + +WARL, by allowing implementors to choose the value, prevents and prohibits the critical and necessary raising of an exception that would begin the JIT process in the case of ongoing standards evolution. + +Without this opportunity, an implementation has no way of knowing how to JIT emulate any given conflicting opcode. It is as if the c++ standard was given the similar opportunity to completely ignore the "using namespace" prefix! + +-- + Ok so I trust it's now clear why WLRL (thanks Allen) is needed. When Dan raised the WARL concern initially a situation was masked by the conflict, that if gone unnoticed would jeapordise ISAMUX/ISANS entirely. Actually, two separate errors. So thank you for raising the question. -- 2.30.2