README: Add Mesh required Kernel Configuration section

Not all distributions include all required mesh crypto support.  This
adds a section with known kernel required options.

Change-Id: I8b62d79ffb4688426f1b37a27be494abcd1eb00a
Signed-off-by: Anupam Roy <anupam.r@samsung.com>

diff --git a/README b/README
index a0d256f..ebf1c43 100755 (executable)
--- a/README
+++ b/README
@@ -57,6 +57,31 @@ When neither --enable-mesh nor --enable-btpclient is specified, then this
 part is irrelevant and Embedded Linux library is not required.
 
 
+Kernel Build Options (for Mesh)
+===============================
+
+The Mesh daemon uses kernel provided crypto utilities to perform security
+functions required of Bluetooth Mesh. Many standard distributions currently
+enable all required crypto features, but a few notable distributions do
+not.
+
+If Mesh Cryptography is not working, the following configuration options
+may need to be enabled, and the kernel rebuilt.
+
+1. A minimum of kernel version 4.9 or later is required
+
+2. The kernel must at a minimum have the following .config options turned on:
+       CONFIG_CRYPTO_USER
+       CONFIG_CRYPTO_USER_API
+       CONFIG_CRYPTO_USER_API_AEAD
+       CONFIG_CRYPTO_USER_API_HASH
+
+       CONFIG_CRYPTO_AES
+       CONFIG_CRYPTO_CCM
+       CONFIG_CRYPTO_AEAD
+       CONFIG_CRYPTO_CMAC
+
+
 Configuration and options
 =========================