(no commit message)

diff --git a/openpower/sv/ldst.mdwn b/openpower/sv/ldst.mdwn
index aaeba9009eb39af72ef2e96f79b6b77d8ee73d10..b45cef6653c90e3c0950ce20826f18f2833c5f5f 100644 (file)
--- a/openpower/sv/ldst.mdwn
+++ b/openpower/sv/ldst.mdwn
@@ -554,5 +554,16 @@ because the generic abstracted concept of "Remapping", when applied to
 LD/ST, will give that same capability, with far more flexibility.
 
 Also LD/ST with immediate has a Pack/Unpack option similar to VSX
-'vpack' and 'vunpack'.
+'vpack' and 'vunpack', as well as the VSX Pixel instructions. Enabling
+this mode on SubVectors is straightforward and does not involve
+the setup cost of REMAP. Unlike REMAP, Pack/Unpack on LD/ST does not have
+Saturation (or Fail-first) at the same time.
+
+*Programmer's note: a decision on what is best if combining Saturation
+with Pack/Unpack is required will depend on resources.  REMAP will
+require less registers but is more costly to set up. On the other
+hand LDST Pack/Unpack followed by Saturated MV or arithmetic requires
+intermediary registers at full width prior to reduced saturated width.
+A balanced decision is therefore needed*.
+