add comment docstring about POWER9 simulator

diff --git a/src/soc/decoder/isa/caller.py b/src/soc/decoder/isa/caller.py
index 6541a56c5d769a08f2b3f619cac9b90a05b356da..532957e87467ecc9496fa872ce6ba249c11d690d 100644 (file)
--- a/src/soc/decoder/isa/caller.py
+++ b/src/soc/decoder/isa/caller.py
@@ -1,3 +1,10 @@
+"""core of the python-based POWER9 simulator
+
+this is part of a cycle-accurate POWER9 simulator.  its primary purpose is
+not speed, it is for both learning and educational purposes, as well as
+a method of verifying the HDL.
+"""
+
 from functools import wraps
 from soc.decoder.orderedset import OrderedSet
 from soc.decoder.selectable_int import (FieldSelectableInt, SelectableInt,