Data Usage Docs in Android 4.0 for Systems Integrators.

Change-Id: I65606843ebe5396037c43cf633a0b8c536bfaa1d
diff --git a/src/tech/datausage/kernel-changes.md b/src/tech/datausage/kernel-changes.md
new file mode 100644
index 0000000..f89847f
--- /dev/null
+++ b/src/tech/datausage/kernel-changes.md
@@ -0,0 +1,29 @@
+<!--
+   Copyright 2012 The Android Open Source Project
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+-->
+
+This is a summary of the main changes in the kernel that diverge from mainline.
+
+* added net/netfilter/xt_qtaguid*
+* imported then modified net/netfilter/xt_quota2.c from xtables-addons project
+* fixes in net/netfilter/ip6_tables.c
+* modified ip*t_REJECT.c
+* modified net/netfilter/xt_socket.c
+
+A few comments on the kernel configuration:
+
+* xt_qtaguid masquerades as xt_owner and relies on xt_socket and itself relies on the connection tracker.
+* The connection tracker can't handle large SIP packets, it must be disabled.
+* The modified xt_quota2 uses the NFLOG support to notify userspace.