diff -r a87d4324e804 README
--- a/README	Sat Oct 29 17:01:07 2016 +0200
+++ b/README	Sat Oct 29 21:28:03 2016 +0200
@@ -85,6 +85,50 @@
 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 $PATH environment variable and it must have the same
+package version as the Python source being cross-built (for example python3.6).
+
+One way to ensure that the previous rule is followed is to build the native
+python from the same source first. For example:
+
+    mkdir python-native build install
+    cd python-native
+    /path/to/source/configure && make
+    export PATH=$(pwd):$PATH
+    cd ../build
+    /path/to/source/configure --host=<triplet> --build=<triplet> \
+        ac_cv_file__dev_ptmx=no ac_cv_file__dev_ptc=no \
+        && make DESTDIR=../install install
+
+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, so you must add
+the '--prefix' option to the configure command given above, specifying the path
+where the standard library will be installed so that the python interpreter can
+find it. For example if you set '--prefix=/sdcard/org.github.my_python' then
+this will be the value of sys.prefix and the standard library must be installed
+on the Android device at /sdcard/org.github.my_python/lib/python3.6. 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).
+
+On Android the application binaries are installed on /data as the sdcards are
+mounted noexec. Continuing with the previous example, the binaries are
+installed at /data/data/org.github.my_python following the same directory
+hierarchy as the one found after 'make install' below $DESTDIR/$PREFIX and
+including the shared libraries of the extension modules. Thus those libraries
+must be installed at /data/data/org.github.my_python/lib/python3.6/lib-dynload.
+Note that you do not need to specify the
+'--exec_prefix=/data/data/org.github.my_python' configure option, although this
+may be safer (see the large comment in Modules/getpath.c of the Python source
+code).
+
+
 What's New
 ----------