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Platform SDK

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Mer platform SDK

To avoid any confusion, there are two types of SDKs: Application SDKs and Platform SDKs. Application SDK's are the ones that deal with Qt applications and libraries, HTML5, etc, while Platform SDK's are for developing the platform, compiling native code and other things revolving around the platform developer/hacker needs.

The platform SDK aims to offer a installable disk image that can be run on virtual machines (typically) or actual hardware, which contains tools like Scratchbox2, MIC (image creator), spectacle, osc, qemu, etc preinstalled, to make it easier for a developer to work with Mer.

Please note that the platform SDK is a work on progress. The work for making the sdk was kicked off January 13 2012. If you are willing to contribute to the effort, please do so.

Using the platform SDK

Please note that this is a DRAFT and not all bits and pieces are in place yet. Also things might and most likely will change.

Installation / setup

The platform SDK is provided as a rootfs tarball that contains essential tools for Mer platform development along with a helper script to enter the rootfs.

Please note that the platform SDK requires that you're using a Linux distribution (one in a virtual machine works as well).

To setup the SDK:

  • Download the latest stable SDK rootfs tarball
cd $HOME
curl -k -O
  • Create directory for the SDK rootfs and extract the tarball as root or with sudo
mkdir $HOME/mer-sdk && cd $HOME/mer-sdk
sudo tar --numeric-owner -p -xjf $HOME/mer-sdk-x86-chroot-latest.tar.bz2

Entering chroot

The platform SDK rootfs contains a helper script to enter the chroot named 'mer-sdk-chroot'. The helper script is located the the root directory (/) of the rootfs. It requires you to have sudo ability.

To enter the rootfs with the helper script do

sudo $HOME/mer-sdk/mer-sdk-chroot

You should find that you are operating under your normal username and that your home directory is available as /home/<username> and any other mountpoints are mounted under /parentroot/*

You have sudo rights automatically.

Note: Be sure that the bind-mounts(especialy the home directory) are all umounted after you leave the chroot environment. You can use 'cat /proc/self/mountstats' to check it. If it is not umounted, you should umount it manually after you exit the chroot environment.

Note: On my ubuntu11.10, the umount is done automatically.

Idea: To differentiate the SDK from one's normal shell we could set the prompt to "[Mer]$PS1" while in the chroot. currently it's not that clear if you're in it or not.

Advanced details

The usage for the helper script is:

 mer-sdk-chroot [-u <user>] [-m <all|none|home>] [<SDK root path>]
    Use the Mer SDK
      -u  System user to link into SDK (not needed if using sudo)
      -m  Devices to bind mount from host: none, all (default)
          or just $HOME

The script will bind mount any 'normal' mountpoints it finds into the chroot onto /parentroot in the SDK

Additionally, if the user specified has a .mersdkrc in their $HOME, it will be sourced prior to entry and if an enter_sdk() function is declared this will be run as root. As the user exits the chroot, if a leave_sdk() function is declared, it will be executed. This could be used to create symlinks from any /parentroot/data type filesystems into the SDK root I use the hook to create /maemo and /maemo/mer symlinks to mountpoints in the parentroot. eg:

# This file is sourced by
# This function is called just before the root is entered.
# $sdkroot is the path to the SDK /
enter_sdk() {
    [[ -e ${sdkroot}/maemo ]] || ln -s parentroot/maemo ${sdkroot}
    [[ -e ${sdkroot}/mer ]] || ln -s parentroot/maemo/mer ${sdkroot}

Basic tasks

Building an image

Mer images are build using mic image creator. Mic takes a kickstart file that defines the image to be created as input. To create a Mer image with the platform SDK simply call mic as you would do on any other system. For example

As a test this should make a new local SDK rootfs image

curl -k -O
sudo mic create fs mer-sdk-x86-chroot-latest.ks -o . --pkgmgr=yum --arch i486 --compress-disk-image=tar.bz2

Running osc

Since your home directory has been linked into the SDK then osc commands should work as normal.

osc ls

SDK contents

The platform SDK's rootfs has some useful packages preinstalled that are listed below. If you're missing something you can use zypper to install the needed extra packages or if not available in the repositories compile them yourself.

  • osc and build
  • mic

Compiling with the SDK



The SDK includes tools needed to create rpm packages for Mer.


Hosting repositories

To make installing created packages easier you can host your own rpm repository with the SDK and install packages to your target device from there.


Development Documentation

Below you will find information about the development of the platform SDK itself.


The following requirements were agreed on the initial platform sdk brainstorming meeting (things may change)

  • Platform SDK needs to be able to function without an OBS account or access to an OBS.
  • Offline compilation must be possible
  • Clearly document the difference between platform SDK and application SDK.
  • Document the SDK tools for easier porting to new Linux distributions (if all SDK tools, and nothing else, comes from a single OBS project, that might be enough documentation).
  • seperation of user /home and 'sdk'
  • need short path from: code, build, deploy, boo
  • minimal http server to SDK for built rpm repo serving

Sources and packages



SDK team meeting minutes

Usefull links and further reading

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