From: lkcl <lkcl@web>
Date: Tue, 14 Jun 2022 23:52:58 +0000 (+0100)
Subject: (no commit message)
X-Git-Tag: opf_rfc_ls005_v1~1773
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=d20b1c029aa4e268859399c821e3f18e59efe92b;p=libreriscv.git

---

diff --git a/openpower/sv/svp64_quirks.mdwn b/openpower/sv/svp64_quirks.mdwn
index 34920fdb4..85ffc48cb 100644
--- a/openpower/sv/svp64_quirks.mdwn
+++ b/openpower/sv/svp64_quirks.mdwn
@@ -224,6 +224,22 @@ for the type of operation (Branch, CRs, Memory, Arithmetic),
 and each Category has its own relevant but
 ultimately rational quirks.
 
+# Abstraction between Prefix and Suffix
+
+In the introduction paragraph, a great fuss was made emphasising that
+the Prefix is kept separate from the Suffix.  The whole idea there is
+that a Multi-issue Decoder and subsequent pipelines would in no way have
+"back-propagation" of state that can only be determined far too late.
+This *has* been preserved, however there is a hiccup.
+
+Examining the Power ISA 3.1 a 64-bit Prefix was introduced, EXT001.
+The encoding of the prefix has 6 bits that are dedicated to letting
+the hardware know what the remainder of the Prefix bits mean: how they
+are formatted, even without having to examine the Suffix to which
+they are applied.
+
+SVP64 has such pressure on its 24
+
 # Single Predication
 
 So named because there is a Twin Predication concept as well, Single