Cross-compiling Synapse for raspberry (ARM) and other architectures ¶

This is a quick howto on how i cross compiled synapse for the raspberrypi, using qemu to emulate the arm cpu architecture. This is the least tricky methode to cross compile, but also the slowest.

I used arch linux on my host system and debian on the rasp.

Learn your host system how to handle arm binaries ¶

1. Steal a statically compiled qemu-arm from some distro: ¶

its a shame archlinux doesnt have a static qemu :(

[root@lab1 tmp]# cd /tmp
[root@lab1 tmp]# mkdir qemu
[root@lab1 tmp]# cd qemu
[root@lab1 qemu]# dpkg -x /home/psy/Downloads/qemu-user-static_1.1.2+dfsg-2_amd64.deb  .
[root@lab1 qemu]# cp usr/bin/qemu-*-static /usr/bin

2. learn your kernel how to handle arm binaries ¶

[root@lab1 binfmts]# cat /usr/share/binfmts/qemu-arm          
package qemu
interpreter /usr/bin/qemu-arm-static
magic \x7fELF\x01\x01\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x28\x00
mask \xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff\xff

[root@lab1 binfmts]# update-binfmts --import

Set up the build environment ¶

1. copy the rootfilesystem from your raspberry ¶

We just copy the whole rootfs, so we have an exact copy of the environment we want to cross compile for:

[root@lab1 psy]# rsync -ax root@192.168.13.238:/ rasprootfs
root@192.168.13.238's password: 
....

2. entering the build environment ¶

The only thing you have to do to be able to enter the environent is copy qemu-arm-static into it:

[root@lab1 psy]# cp /usr/bin/qemu-arm-static rasprootfs/usr/bin/
[root@lab1 psy]# chroot rasprootfs/
root@lab1:/# uname -a
Linux lab1 3.6.5-1-ARCH #1 SMP PREEMPT Wed Oct 31 20:57:39 CET 2012 armv7l GNU/Linux

w000h...now we can chroot to the local raspberry environment and start to compile stuff!

compiling and installing synapse = ¶

1. install dependencies neccesary to compile synapse ¶

Inside the chroot do this:

root@lab1:~/Synapse# apt-get install libboost-all-dev cmake libcurl4-openssl-dev liboauth-dev libvlc-dev
Reading package lists... Done
Building dependency tree       
Reading state information... Done

(....... takes a while)

2. clone the source tree ¶

root@lab1:~# git clone git://github.com/psy0rz/Synapse.git
Cloning into 'Synapse'...
remote: Counting objects: 4533, done.
remote: Compressing objects: 100% (1258/1258), done.
remote: Total 4533 (delta 3311), reused 4429 (delta 3207)
Receiving objects: 100% (4533/4533), 2.04 MiB | 835 KiB/s, done.
Resolving deltas: 100% (3311/3311), done.

wow...even while emulated git STILL is superquick! git is awesome :)

3. compile it ¶

root@lab1:~# cd Synapse/
root@lab1:~/Synapse# cmake .
-- The C compiler identification is GNU 4.6.3
......

root@lab1:~/Synapse# make -j 4 
Scanning dependencies of target test_http_json
Scanning dependencies of target pl_dir