From: lkcl <lkcl@web>
Date: Sun, 29 May 2022 09:13:26 +0000 (+0100)
Subject: (no commit message)
X-Git-Tag: opf_rfc_ls005_v1~2045
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=c3745c2ea3cd6476d18c608b3fdebb279233f298;p=libreriscv.git

---

diff --git a/openpower/sv.mdwn b/openpower/sv.mdwn
index ef14c4f46..13e7812fb 100644
--- a/openpower/sv.mdwn
+++ b/openpower/sv.mdwn
@@ -38,6 +38,40 @@ Advantages of these design principles:
   but off of Vectorisation ISAs as well.  No more separate Vector
   instructions.
 
+# Major opcodes summary
+
+Please be advised that even though below is entirely DRAFT status, there
+is considerable concern that because there is not yet any two-way
+day-to-day communication established with the OPF ISA WG, we have
+no idea if any of these are conflicting with future plans by any OPF
+Members.  **The External ISA WG RFC Process is yet to be ratified
+and Libre-SOC may not join the OPF as an entity because it does
+not exist except in name. Even if it existed it would be a conflict
+of interest to join the OPF, due to our funding remit from NLnet**.
+We therefore proceed on the basis of making public the intention to
+submit RFCs once the External ISA WG RFC Process is in place and,
+in a wholly unsatisfactory manner have to *hope and trust* that
+OPF ISA WG Members are reading this and take it into consideration.
+
+**None of these Draft opcodes are intended for private custom
+secret proprietary usage. They are all intended for entirely
+public, upstream, high-profile mass-volume day-to-day usage at the
+same level as add, popcnt and fld**
+
+* SVP64 requires 25% of EXT01 (bits 6 and 9 set to 1)
+* bitmanip requires two major opcodes (due to 16+ bit immediates)
+  those are currently EXT022 and EXT05.
+* brownfield encoding in one of those two major opcodes still
+  requires multiple VA-Form operations (in greater numbers
+  than EXT04 has spare) currently in EXT022 (which is under
+  severe design pressure)
+* space in EXT019 next to addpcis and crops is recommended
+* many X-Form opcodes currently in EXT022 have no preference
+  for a location at all, and may be moved to EXT059, EXT019,
+  EXT031 or other much more suitable location.
+
+# Sub-pages
+
 Pages being developed and examples
 
 * [[sv/overview]] explaining the basics.