diff -r 85e2cfe5b12d README
--- a/README	Sun Oct 30 04:30:36 2016 +0000
+++ b/README	Mon Oct 31 16:36:48 2016 +0100
@@ -85,6 +85,40 @@
 performance gains.
 
 
+Cross Compiling on unix
+-----------------------
+
+The cross-compilation of Python requires a natively installed python to run
+Python scripts at multiple stages in the build process.  The path to this
+native python must be set in the $PATH environment variable and it must have
+the same package version as the Python source being cross-built (for example
+python3.6).
+
+One way to ensure that the previous rule is followed is to build the native
+python from the same source first.  For example:
+
+    mkdir python-native cross-build install
+    cd python-native
+    ../configure && make
+    export PATH=$(pwd):$PATH
+    cd ../cross-build
+    ../configure --host=<triplet> --build=<triplet> \
+        --enable-ipv6 ac_cv_file__dev_ptmx=no ac_cv_file__dev_ptc=no \
+        && make DESTDIR=../install install
+
+If the target does not support ipv6, use --disable-ipv6 instead.  If the target
+Python can use /dev/ptmx or /dev/ptc to implement os.openpty(), set the
+corresponding argument to "yes".
+
+On Android /usr/local does not exist and cannot be created and you must add the
+--prefix option to configure, specifying the path where the standard library
+will be installed so that the python interpreter can find it.  Note that you
+still need to use DESTDIR in the make install command (see
+https://www.gnu.org/software/make/manual/html_node/DESTDIR.html).  The shared
+libraries of the extension modules may be installed separately using the
+--exec-prefix option.
+
+
 What's New
 ----------