jcache docs

1 files changed, 5 insertions, 1 deletions

diff --git a/emcc b/emcc
index 7e7efe6d..677f5b65 100755
--- a/emcc
+++ b/emcc
@@ -335,7 +335,11 @@ Options that are modified or new in %s include:
                            builds - where you are compiling a large
                            program but only modified a small part of it -
                            to be much faster (at the cost of more disk
-                           IO for cache accesses).
+                           IO for cache accesses). Note that you need
+                           to enable --jcache for both loading and saving
+                           of data, so you must enable it on a full build
+                           for a later incremental build (where you also
+                           enable it) to be sped up.
 
   --clear-cache            Manually clears the cache of compiled
                            emscripten system libraries (libc++,