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= Mer on Raspberry Pi =

This page details the steps required to bring up a development environment which can be used to create a basic Mer image.

The hardware adaptation is maintained in the project [https://build.pub.meego.com/project/packages?project=CE%3AAdaptation%3ARaspberryPi CE:Adaptation:RaspberryPi]

=== Working ===

* Boot with 128M/128M memory split (128M for the ARM, 128M for the GPU)
* Wired networking
* Gstreamer HW accelerated decode using gst-omx
* Audio output through HDMI/audio jack(at least after manual modprobe snd-bcm2835)
* OpenGL ES 2 (not X.Org integrated)
* OpenMax IL decode/render (not X.Org integrated)

=== Not working ===

* HW accelerated Gstreamer video render
* HW accelerated GStreamer video encode
* HW accelerated Gstreamer audio decode/encode
* Accelerated X.Org
* Accelerated Qt
* Qt 5.0
* Qt 4.8

== Install Mer SDK ==

Using the instructions at http://wiki.merproject.org/wiki/Platform_SDK#Mer_platform_SDK install Mer SDK on your host Linux system.  The SDK has been designed to not rely on the host system so you can use your favourite distro. 

Get an account on the community OBS server, ping lbt on #mer freenode IRC channel.

edit .oscrc to set server to api.pub.meego.com and set user and password

To test the installation follow the instructions for building the SDK image.

== Building a Mer Core Image ==

Here we use the SDK to build an image which can be written to an sdcard which will include bootloader, kernel and a base filesystem which boots X and starts qmlviewer.

Get kickstart file 

 curl -k -O  https://github.com/snowcap-electronics/kickstarts/raw/master/rpi/mer-rpi.ks

To work around a mic issue zypper in the following package to the SDK

 sudo zypper in syslinux-extlinux

Use the mic tool to create the image using the kickstart file

 sudo mic create raw mer-rpi.ks -o . --pkgmgr=yum --arch=armv6l

Once the image has been produced write to your sdcard (you may need to use sudo below if groups are not properly set):

 dd of=/dev/sdX if=mer-rpi-mmcblk0p.raw bs=4M

Place in RaspberryPi and boot.

== Host SDK Development using SB2 ==

Cross-compiling on the host SDK (as opposed to compiling natively on device) is possible by creating a ''target'' (an unpacked rootfs) and using sb2 to "emulate" the ARM device.

=== Step-by-step Setup ===

Step one is to create the target rootfs. This can be done with '''mic''' using the same ''kickstart'' file used to create the image:

 sudo mic create fs mer-rpi.ks -o /path/to/target --arch=armv6l

This will create a ''/path/to/target/mer-rpi'' directory with a rootfs that contains all the default packages from that ks.

Step two is changing the permissions so we can write anywhere on the rootfs:

 sudo chown -R $USER.mer mer-rpi

Step three is initializing the sb2 target (yes, a lot of options there):

 cd mer-rpi
 sb2-init -A armv6l -M armv6l -d -L --sysroot=/ -C --sysroot=/ -c /usr/bin/qemu-arm-dynamic -m sdk-build -n -N -t / mer-rpi /opt/cross/bin/armv6l-meego-linux-gnueabi-gcc

There will be errors from sb2-init (concerning ld and host-gcc), but it should be safe to ignore them.

Step four is to fix a quirk about /var/run in the target being a symlink, sb2 doesn't like this:

 rm var/run
 mkdir var/run

Step five is to rebuild and refresh the packaging system so we can install devel packages:

 sb2 -m sdk-install -R rpm --rebuilddb
 sb2 -t mer-rpi -m sdk-install -R zypper ref

=== Building RPi Examples ===

As an example of how to use sb2 to build, we shall build the [https://github.com/raspberrypi/firmware/tree/master/opt/vc/src/hello_pi RPi examples]. (TBD: sane way to get them)

First off, we know beforehand that we will need the rpi graphics and freetype devel packages installed to compile the examples. Usually the exact dependencies are either in the README or INSTALL of the project or (sadly often) found out by building and failing. We also need ''make'' and ''gcc'' in the target to compile.

To install, we will use sb2 in ''sdk-install'' mode and also request to fake that we are root user (as we did in setup too). This will enable us to write to the rootfs, normally it is considered read-only, and trick the tools to think we have super powers:

 sb2 -m sdk-install -R zypper install gcc make gfx-rpi-devel gfx-rpi-libEGL-devel gfx-rpi-libGLESv2-devel gfx-rpi-libOMXIL-devel freetype-devel 

NOTE: sometimes it's necessary to be on the top directory of the target to successfully run commands in the sdk-install mode. If a command fails mysteriously, try that first.

Next we create a symbolic link from /usr (where the libs ''should'' be) to mer-pi/opt/vc (where the libs ''are'' in RPi "official" images). This way we avoid changing the include paths in the project (which would be a valid fix as well):

 ln -s /usr opt/vc

Then we simply go to the ''hello_pi'' directory and invoke the build script (which just goes through the example directories calling make in them) through sb2:

 sb2 ./rebuild.sh

If everything is set up right, you should in a moment have cross-compiled binaries to copy to your device.

NOTE: couple of examples (hello_audio & hello_video) need -lpthread to be added to their LDFLAGS to link succesfully, due to the ''ilclient'' helper lib requiring it.

The same principle works for most other projects as well, just install the dependencies and run the build commands through sb2.

(TBD: how to install non-packaged dependencies?)

= Maintainers =

For questions, suggestions and contributions you can ping the following persons in #mer @ Freenode
* cristi
* kulve
* vgrade
* zuh

= For maintainers =

== Wiki page TODO ==

* Add: QtCreator Instructions

== Updating packages ==

=== bootloader-rpi ===

 git clone https://github.com/raspberrypi/firmware.git
 rm firmware/boot/kernel*
 tar zcf firmware-boot-<git sha>.tgz firmware/boot

=== gfx-rpi ===

 git clone https://github.com/raspberrypi/firmware.git
 tar zcf firmware-opt-<git sha>.tgz firmware/hardfp/opt/vc/ firmware/opt/vc/

=== gst-omx-rpi ===

 git clone git://anongit.freedesktop.org/gstreamer/gst-omx
 cd gst-omx
 git checkout -b raspberry remotes/origin/raspberry
 ./autogen.sh && make dist
 mv gst-omx-0.10.0.1.tar.gz gst-omx-raspberry-0.10.0.1-<git sha>.tar.gz

=== gst-plugins-bad-free, gst-plugins-base ===

* Branched from Mer Core
* gst-plugins-base upgraded to 0.10.36
* Added --with-audioresample-format=float for ARMv6 in gst-plugins-base.spec

=== kernel-adaptation-rpi ===

* Download latest .tar.gz from https://github.com/raspberrypi/linux (branch rpi-3.2.27)

=== mkimage-rpi ===

 git clone https://github.com/raspberrypi/tools.git
 tar zcf tools-mkimage-<git sha>.tar.gz tools/mkimage