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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.
SDK Requirements
The chroot SDK will run on most modern linux machines. It needs:
- about 400Mb free space to install
- hundreds of Mb for rpm caches for osc and mic
- Generic x86 CPU
- user must have sudo rights
WARNING
The SDK consists of a directory tree and when you 'mount' the SDK you will link your home directory, root directory and any data directories within this tree.
Because of this you *MUST* 'umount' the SDK before deleting it - if you don't then you *WILL* lose data.
If you are unfamiliar with bind mounts, the safest way to uninstall is to reboot your machine and remove the SDK *BEFORE* using the sdk 'mount' command.
Please do not be alarmed by this - we're simply letting you know that running an "rm -rf" command in the wrong place is dangerous. It's better to explain this in big letters than risk someone losing data by mistake :)
Obviously people working on SDK development and testing should take particular care.
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 well).
The SDK can be installed to any location with enough space - we'll use /srv/ as per the Linux FHS (feel free to adapt the commands to use any other location).
The installation path must contain an intermediate directory called 'sdks' which only has Mer SDKs inside. eg /srv/mer/sdks/sdk/...
To setup the SDK:
Check: https://img.merproject.org/images/sdk/latest/images/mer-sdk-i486-chroot/ for the name of the latest tarball
- Download the latest stable SDK rootfs tarball.
cd $HOME curl -k -O https://img.merproject.org/images/sdk/latest/images/mer-sdk-i486-chroot/<LATEST>
- Create directory for the SDK rootfs and extract the tarball as root or with sudo
sudo mkdir -p /srv/mer/sdks/sdk cd /srv/mer/sdks/sdk sudo tar --numeric-owner -p -xjf $HOME/mer-sdk-i486-chroot-<LATEST>.tar.bz2
SDK control script
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.
As mentioned, the SDK is location independent so it uses the location of the helper script to determine which SDK to enter.
Connect the SDK using 'mount'
You need to connect the SDK before using it. This only needs to be done once (well, once each time you boot your machine) and it connects things like /proc and $HOME in the SDK. It also links /parentroot of the SDK to your normal / directory.
Under normal use the SDK does not need to be disconnected. As per the warning above, you should disconnect using 'umount' before removing the SDK (see remove/disconnect info below)
To connect run:
/srv/mer/sdks/sdk/mer-sdk-chroot mount
You can now use the SDK from multiple terminals at once.
Entering chroot
Before entering the SDK you may want to make an SDK equivalent of ".profile" to give you a nice prompt to remind you that you are in the SDK:
echo 'PS1="MerSDK $PS1"' >> ~/.mersdk.profile
To enter the rootfs with the helper script run
/srv/mer/sdks/sdk/mer-sdk-chroot enter
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.
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:
(Check: https://img.merproject.org/images/sdk/latest/images/mer-sdk-i486-chroot/ for the name of the latest KickStart file)
curl -k -O https://img.merproject.org/images/sdk/latest/images/mer-sdk-i486-chroot/<LATEST> 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
Compiling with the SDK (FIXME)
Cross compilation tools are not currently available in the SDK out of the box. To setup cross compiling for N950 (armv7hl) do the following inside the sdk chroot
sudo zypper ref sudo zypper in scratchbox2 qemu-usermode
add repository containing cross compiler and install needed packages from there
sudo zypper ar http://releases.merproject.org/releases/0.20120209.1/builds/armv7hl/packages/ cross sudo zypper ref sudo zypper in cross-armv7hl-gcc cross-armv7hl-binutils
extract Nemo N950 rootfs to for example your home directory
mkdir -p $HOME/n950rootfs cd $HOME/n950rootfs sudo tar xjvf /path/to/nemo-n950-image.tar.bz2
Set file permissions for the n950 rootfs
sudo chown -R <your username> n950rootfs
you might also need to give write permissions to some places like bin, sbin and so on.
sudo chmod u+w bin
initialize scratchbox2
cd $HOME/n950rootfs sb2-init -d -L --sysroot=/ -C --sysroot=/ -c /usr/bin/qemu-arm-dynamic nemo-n950 /opt/cross/bin/armv7hl-meego-linux-gnueabi-gcc
if you get an error compaining about tmp do
sudo chmod 777 /tmp
and try again. the compiler should now work but you are still missing libraries to compile against. Install what you need into the n950 rootfs by
sb2 -eR zypper ref sb2 -eR zypper install ...
If the installation fails due to permission errors give your user write permissions to the places the packages are being installed and retry. After this you can compile for example a c hello world by
cat << "EOF" > hello.c #include <stdio.h> int main(int argc, char **argv) { printf("Hello\n"); return 0; } EOF sb2 gcc hello.c -o hello
verify that the compilation worked
$ file hello hello: ELF 32-bit LSB executable, ARM, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.25, not stripped $ sb2 ./hello Hello
Packaging
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.
TODO
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
Upgrading the SDK
Within the SDK you can update and upgrade your tools using:
sudo zypper ref sudo zypper up
New tools can be installed using
sudo zypper in <package>
Advanced details
The usage for the helper script is:
usage: mer-sdk-chroot [<enter>] [-u <user>] [-r <SDK root path>] mer-sdk-chroot mount [-u <user>] [-m <all|none|root|home>] [-r <SDK root path>] mer-sdk-chroot umount [-r <SDK root path>] This is the Mer chroot SDK. For information see http://wiki.merproject.org/wiki/Platform_SDK The SDK has 3 commands: enter (default) mount umount enter Used to enter the SDK and begin working. The SDK bash shell is a login shell. See below for .profile handling Must be preceded by a 'mount' to setup the SDK. May be used in multiple terminals and simply enters the chroot mount Used to setup the SDK mountpoints. Only needed once per login session umount Used to clean up the SDK mountpoints before removing the SDK. Options: -u System user to link into SDK (not needed if using sudo) -m Devices to bind mount from host: none, all (default) root, home -r The root of the SDK to use - normally derived from the pathname of mer-sdk-chroot Profile Entering the SDK runs the user's normal .profile and any (SDK) system profile entries. It will not execute the host's system profile entries. The environment variable MERSDK is set to 1 to allow .profile to detect the SDK. If the user has a ~/.mersdk.profile then it is sourced after the normal .profile handling (this allows the common use case of setting a profile to be handled). Hooks If the user specified has a .mersdkrc in their $HOME, it will be sourced to allow hook functions to be defined. Hooks are run as root. No commands should be executed immediately. These hooks are usually used to define symbolic links from any /parentroot/data type filesystems into the SDK root to setup system specific shared caches or filesystem layouts etc
Sharing mic and osc caches
You can use the ~/.mersdkrc file to check and link the standard mic and osc cache directories to those in parentroot.
Note that multiple *concurrent* instances of mic should not share the same cache (it's OK to share from different SDKs and different terminals provided they're not running and accessing the cache at the same time).
Here's some code you can use in ~/.mersdkrc to share a mic cache:
if [[ ! -e ${sdkroot}/var/tmp/mic ]]; then
mkdir -p ${sdkroot}/var/tmp/mic
fi if [[ ! -e ${sdkroot}/var/tmp/mic/cache && ! -h ${sdkroot}/var/tmp/mic/cache ]]; then
ln -s /parentroot/var/tmp/mic/cache ${sdkroot}/var/tmp/mic/cache
fi
In your ~/.oscrc file there is a line:
packagecachedir = <something>/build-pkg-cache
If this is under $HOME then it will be shared anyway; otherwise do something similar to the mic cache code above.
Multiple SDKs
You should be able to install and connect to multiple SDKs at the same time.
Removing and disconnecting the SDK
Under normal use the SDK does not need to be disconnected; it's only usually needed when you want to remove an instance of the SDK.
To disconnect run:
/srv/mer/sdks/sdk/mer-sdk-chroot umount
Be sure that the bind-mounts(especialy the home directory) are all umounted after you disconnect the SDK. You can use 'cat /proc/self/mountstats' to check it. If it is not umounted cleanly, you should umount it manually after you exit the chroot environment.
The SDK does warn you if umounts fail. It also uses 'lazy' umounts which means that the mountpoints will go away as soon as the kernel can clean them (typically when processes exit or terminals cd out of the mounted directories.)
Once the SDK has been cleanly unmounted, it may be removed manually.
Development Documentation
Below you will find information about the development of the platform SDK itself.
Requirements
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
- COBS project : Mer:Tools:Testing : https://build.pub.meego.com/project/monitor?project=Mer%3ATools%3ATesting
- basic kickstart: https://build.pub.meego.com/package/files?package=sdk-kickstarter-configs&project=home%3Albt%3Abranches%3AMer%3ATools%3ATesting
- rootfs an mount script: https://img.merproject.org/images/
- the script's git version is hosted at https://github.com/lbt/sdk-kickstarter-configs
QA
TBD
SDK team meeting minutes
- 13.1.2012 http://mer.bfst.de/meetings/mer-meeting/2012/mer-meeting.2012-01-13-18.02.html
- 28.1.2012 http://mer.bfst.de/meetings/mer-meeting/2012/mer-meeting.2012-01-28-10.04.log.html
- 24.2.2012 http://mer.bfst.de/meetings/mer-meeting/2012/mer-meeting.2012-02-24-16.01.html