Hacking b2g on Raspberry Pi: Difference between revisions

This page is intended for folks who are interested in building and running b2g on Raspberry Pi devices.

* graphics are barely functional.  b2g can allocate video memory and submit jobs to the GPU, but there are numerous glitches in the graphics pipeline that result in distorted screen contents. {{bug|1072138}} {{bug|1072140}}

* HIDs have not yet been tested.  They most likely work. {{bug|1072502}}

* Wi-Fi dongles have not yet been tested.  Most likely they don't work yet. {{bug|1072522}}

* audio output has not been tested.  It may not work. {{bug|1072499}}

* system performance has not yet been tuned for the RPi.  Some things may be slower than expected.

Install the [https://developer.mozilla.org/en-US/Firefox_OS/Firefox_OS_build_prerequisites b2g build prerequisites].  For the time being, only linux is supported as a build environment.  Note that Ubuntu 12.04 is the best-supported development OS.  If you're not running Ubuntu 12.04 on your development machine, you can install it as virtual machine and build in there.

The config.sh step can take quite a while, because it downloads a large amount of data.  Once that finishes, build b2g

Eventually Mozilla will host prebuilt b2g images for the Raspberry Pi.  For now, you'll need to build your own image by following the steps above.

To hack b2g on the RPi, you'll want to set up a few things.  First, a serial console is strongly recommended.  (A serial console is basically required for kernel development.) You can purchase a serial-to-USB or serial-port connector for your RPi.  Some RPi kits also include one of these.  A common serial-to-USB adapter included in RPi kits requires you to connect the black lead to pin 6 (ground), the white lead to pin 8 (GPIO14, UART0_TXD), and the green lead to pin 10 (GPIO15, UART0_RXD).  You don't need to connect the red lead if your RPi already has a power source.  The b2g kernel is pre-configured to open a serial console for the RPi, so all you need to do is plug the USB cable into your host machine and start up a terminal emulator.  The <code>minicom</code> program works well. On ubuntu, install minicom with the command

  sudo apt-get install minicom

Then connect to your RPi using the command

  minicom -b 115200 -o -D /dev/ttyUSB0

(Replacing <code>/dev/ttyUSB0</code> with the device assigned to your USB-to-serial adapter, if it's not assigned that name.) You should then see terminal output and get a shell prompt.

Note: you must run minicom in a "smart terminal". minicom doesn't work when run inside an emacs shell, and it errors out with a somewhat cryptic message ("No cursor motion capability (cm)"). 

You must create an adb connection for your RPi.  adb is the "android debug bridge" over which diagnostic output is received and development commands are sent.  Usually an adb connection is made over USB, but this hasn't been tested with the RPi.  (The RPi's USB ports are intended to be used in master mode, and it's not yet known whether they will go into slave mode if connected to a host machine through a full-sized USB male-to-male connector.  These cables are also somewhat hard to find.)

 

You can connect adb through the RPi's ethernet port, however.  To connect adb over ethernet, you need to find out your RPi's IP address on your LAN.  You can do this by either looking at your network router's client table, or running the following command on your RPi's serial console

Once you know your RPi's IP address, connect adb by running the following command on your host machine

replacing <code>$IP</code> with your RPi's IP address, of course.  (5555 is the port that the adb server on your RPi listens on.)  To test your adb connect, run the following command on your host

You should a long list of diagnostic messages.  Pressing Ctrl-c stops the logcat output.