Add cross-compilation instructions

[beriberikix]

To start, it would be great to have instructions on how to x-compile wpantund on MacOS/Linux targeting a less-beefy SBC like the Raspberry Pi 3. As a user I've used http://crosstool-ng.github.io/ but I'm sure there are other options out there, especially using automake.

[darconeous]

Yes, one of the downsides to using boost is the crazy resources used while compiling. :(

[DuaneEllis-TI]

the other issue with this type of cross is you need more then the compiler... you need all of the secondary packages and their related header files in your cross build environment.

It's non-trivial to set this up, and I think it is well beyond the scope of 'wpantund' to document this.

[d-bahr]

I have successfully cross-compiled wpantund and wpanctl for a BeagleBone Black via arm-linux-gnueabihf-gcc. Here are the steps. If there's a better place to put this write-up (like on a Wiki page) I would be happy to drop it there.

First, in a clean repo:
sudo bash ./bootstrap.sh

Don't forget to sudo-alternatives the arm-linux-gnueabihf gcc installation (it doesn't seem to do it by default on my installation):
https://askubuntu.com/questions/26498/choose-gcc-and-g-version

sudo update-alternatives --install /usr/bin/arm-linux-gnueabihf-gcc arm-linux-gnueabihf-gcc /usr/bin/arm-linux-gnueabihf-gcc-4.8 10
sudo update-alternatives --install /usr/bin/arm-linux-gnueabihf-g++ arm-linux-gnueabihf-g++ /usr/bin/arm-linux-gnueabihf-g++-4.8 10
sudo update-alternatives --install /usr/bin/arm-linux-gnueabihf-cpp arm-linux-gnueabihf-cpp /usr/bin/arm-linux-gnueabihf-cpp-4.8 10
sudo update-alternatives --install /usr/bin/arm-linux-gnueabihf-gcc-ar arm-linux-gnueabihf-gcc-ar /usr/bin/arm-linux-gnueabihf-gcc-ar-4.8 10
sudo update-alternatives --install /usr/bin/arm-linux-gnueabihf-gcc-nm arm-linux-gnueabihf-gcc-nm /usr/bin/arm-linux-gnueabihf-gcc-nm-4.8 10
sudo update-alternatives --install /usr/bin/arm-linux-gnueabihf-gcc-ranlib arm-linux-gnueabihf-gcc-ranlib /usr/bin/arm-linux-gnueabihf-gcc-ranlib-4.8 10
sudo update-alternatives --install /usr/bin/arm-linux-gnueabihf-gcov arm-linux-gnueabihf-gcov /usr/bin/arm-linux-gnueabihf-gcov-4.8 10

Need to download dbus arm library for armhf builds:

sudo dpkg --add-architecture armhf
sudo apt-get update

Add these lines to /etc/apt/sources.list:

deb [arch=armhf] http://ports.ubuntu.com/ubuntu-ports trusty main
deb [arch=armhf] http://ports.ubuntu.com/ubuntu-ports trusty-updates main
deb [arch=armhf] http://ports.ubuntu.com/ubuntu-ports trusty-backports main
deb [arch=armhf] http://ports.ubuntu.com/ubuntu-ports trusty-security main

Then:
sudo apt-get update

Go to a temporary directory (important!) and run:

sudo apt-get download libdbus-1-dev:armhf
sudo apt-get download libreadline6:armhf
sudo apt-get download libreadline6-dev:armhf
sudo apt-get download libreadline-dev:armhf
sudo dpkg -i libdbus-1-dev_1.4.18-1ubuntu1_armhf.deb
sudo dpkg -i libreadline6_6.3-4ubuntu2_armhf.deb
sudo dpkg -i libreadline6-dev_6.3-4ubuntu2_armhf.deb
sudo dpkg -i libreadline-dev_6.3-4ubuntu2_armhf.deb

The above lines may be different depending on the name of the packages that were downloaded. Also, it may give some errors, but you can safely ignore those. You can delete the temporary directory when you are done.

Finally:
export PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/usr/lib/arm-linux-gnueabihf/pkgconfig

And the moment you've been waiting for (it can be built now):

./configure --sysconfdir=/etc --host=arm-linux-gnueabihf ac_cv_search_readline=/usr/lib/arm-linux-gnueabihf/libreadline.so CC=/usr/bin/arm-linux-gnueabihf-gcc CXX=/usr/bin/arm-linux-gnueabihf-g++ CCLD=/usr/bin/arm-linux-gnueabihf-ld CXXLD=/usr/bin/arm-linux-gnueabihf-ld CFLAGS="$(pkg-config dbus-1 --cflags)"
make -j12

Note: You may need to use this configure step instead (depends on linking/version of D-Bus):

./configure --sysconfdir=/etc --host=arm-linux-gnueabihf ac_cv_search_readline=/usr/lib/arm-linux-gnueabihf/libreadline.so CC=/usr/bin/arm-linux-gnueabihf-gcc CXX=/usr/bin/arm-linux-gnueabihf-g++ CCLD=/usr/bin/arm-linux-gnueabihf-ld CXXLD=/usr/bin/arm-linux-gnueabihf-ld CFLAGS="$(pkg-config dbus-1 --cflags) -pthread" LDFLAGS="-pthread"

The -j12 option sometimes fails. You may need to drop that number (-j4 works nicely) or not use the "-j" option at all.

Also, you can remove the dpkg arm architecture after you're done installing dbus, if the sudo apt-get error messages annoy you.
Follow this link to find and remove libdbus-1-dev (armhf architecture!):
https://askubuntu.com/questions/85748/how-can-i-remove-the-record-of-an-installed-package-without-deleting-any-files
Open /var/lib/dpkg/status. Search for libdbus-1-dev and remove that section (again, armhf architecture only!). Recommend saving a copy of the file as a backup in case something goes wrong.

[Following steps are optional, only the above steps are necessary to remove the apt-get error message]
Then:
sudo dpkg --remove-architecture armhf

And remove the following lines from /etc/apt/sources.list:

deb [arch=armhf] http://ports.ubuntu.com/ubuntu-ports trusty main
deb [arch=armhf] http://ports.ubuntu.com/ubuntu-ports trusty-updates main
deb [arch=armhf] http://ports.ubuntu.com/ubuntu-ports trusty-backports main
deb [arch=armhf] http://ports.ubuntu.com/ubuntu-ports trusty-security main

Lastly, some notes on installing the binaries:

wpantund installs here:
/usr/local/sbin/wpantund

With some plugins here:
/usr/local/libexec/wpantund/…
MAKE SURE YOU CHMOD +X THESE THINGS!

With configuration file here:

/etc/wpantund.conf
/etc/dbus-1/system.d/wpantund.conf

There are also some header files here:
/usr/local/include/wpantund/

wpanctl installs here:
/usr/local/bin/wpanctl

[d-bahr]

The above steps are for Ubuntu 14.04. I just tried those steps for 16.04, and it failed miserably, but I did get it working via a much simpler multiarch setup:

Steps to set up multiarch:
sudo dpkg --add-architecture armhf

Add these lines to /etc/apt/sources.list:

deb [arch=armhf] http://ports.ubuntu.com/ubuntu-ports xenial main
deb [arch=armhf] http://ports.ubuntu.com/ubuntu-ports xenial-updates main
deb [arch=armhf] http://ports.ubuntu.com/ubuntu-ports xenial-backports main
deb [arch=armhf] http://ports.ubuntu.com/ubuntu-ports xenial-security main

Then:
sudo apt-get update

Finally, install the libraries (armhf versions) need to build wpantund:

sudo apt-get install libdbus-1-dev:armhf libdbus-1-3-dev:armhf
sudo apt-get install libreadline-dev:armhf libreadline6-dev:armhf libreadline6:armhf
sudo apt-get install libsystemd0:armhf libsystemd-dev:armhf

Configure dbus pkg-config:
export PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/usr/lib/arm-linux-gnueabihf/pkgconfig

Now you can build away:

sudo bash ./bootstrap.sh
./configure --sysconfdir=/etc --host=arm-linux-gnueabihf ac_cv_search_readline=/usr/lib/arm-linux-gnueabihf/libreadline.so CC=/usr/bin/arm-linux-gnueabihf-gcc CXX=/usr/bin/arm-linux-gnueabihf-g++ CCLD=/usr/bin/arm-linux-gnueabihf-ld CXXLD=/usr/bin/arm-linux-gnueabihf-ld CFLAGS="$(pkg-config dbus-1 --cflags) -pthread" LDFLAGS="-pthread"
make -j4

[darconeous]

Nice! I wonder if we could wrap up all of those steps into a docker container so that it would be easier to do.

[aendle]

Hello
I've tried to cross-compile wpantund for the Omega2+
But I just don't know how. can you help me?

I installed the build system for omega2+ https://onion.io/2bt-cross-compiling-c-programs-part-1/
On Ubuntu lts 16.04
built it with:

For Target System, MediaTek Ralink MIPS
For Subtarget, MT7688 based boards
For Target Profile, Onion Omega2+
included lib boost and dbus

And followed https://github.com/OnionIoT/c-cross-compile-example

My problem is:

In file included from DBUSIPCServer.cpp:32:0:
DBUSIPCServer.h:29:37: fatal error: boost/signals2/signal.hpp: No such file or directory
compilation terminated.

[d-bahr]

I know very little about the Omega2+, but my guess is that running xCompile.sh is overwriting some of the include paths and other compilation configurations created during the ./configure step for wpantund. I would recommend running xCompile.sh with --debug to see what it wants to set for LDFLAGS, CFLAGS, CXX, etc. and then manually enter those values into the ./configure command, then run make as you would normally when building wpantund. The only remaining tricky thing would be to figure out what to specify for --host and I'm not sure what that might be.