Moved zifencetso back into main I chapter, as does not extend base ISA spec.

1 files changed, 17 insertions, 0 deletions

diff --git a/src/rv32.tex b/src/rv32.tex
index 54bbaba..b1bcaca 100644
--- a/src/rv32.tex
+++ b/src/rv32.tex
@@ -1158,6 +1158,9 @@ FENCE.
 \hline
 0000 & \em none & Normal Fence \\
 \hline
+\multirow{2}{*}{1000} & \multirow{2}{*}{TSO} & With FENCE RW,RW: exclude write-to-read ordering \\
+                      &                      & Otherwise: \em Reserved for future use. \\
+\hline
 \multicolumn{2}{|c|}{\em other} & \em Reserved for future use. \\
 \hline
 \end{tabular}
@@ -1171,6 +1174,20 @@ The fence mode field {\em fm} defines the semantics of the FENCE.  A
 FENCE with {\em fm}=0000 orders all memory operations in its
 predecessor set before all memory operations in its successor set. 
 
+The optional FENCE.TSO instruction with {\em fm}=1000 orders all load
+operations in its predecessor set before all memory operations in its
+successor set, and all store operations in its predecessor set before
+all store operations in its successor set.  This leaves non-AMO store
+operations in the FENCE.TSO's predecessor set unordered with non-AMO
+loads in its successor set.
+
+\begin{commentary}
+  The FENCE.TSO encoding was added as an optional extension to the
+  original base FENCE instruction encoding.  The base definition
+  requires that implementations ignore any set bits and treat the
+  FENCE as global, and so this is a backwards-compatible extension.
+\end{commentary}
+
 The unused fields in the FENCE instructions---{\em rs1} and {\em rd}---are
 reserved for finer-grain fences in future extensions.  For forward
 compatibility, base implementations shall ignore these fields, and standard