@@ -168,6 +168,17 @@ case "$cpu" in
+# Default value for a variable defining feature "foo"
+# * foo="no", feature will only be used if --enable-foo arg is given
+# * foo="", feature will be searched for, and if found, will be used
+# * foo="yes", this value vill only be set by --enable-foo flag.
+# feature will searched for, if not found, configure exits with error
+# Always add --enable-foo and --disable-foo command line args. Distributions want
+# to ensure that several features are compiled in, and it is impossible without a
+# --enable-foo that exits if feature is not found