• Tutorial: stream GTK applications and use them in your browser (with GTK+ and Broadway)

    A few days ago I’ve (finally) received my first C.H.I.P.. This is the first 9 dollars microcomputer with a 1Gzh R8 ARM CPU, 512Mb of RAM, 4Gb of on-board space and it includes Wireless B/G/N and Bluetooth 4.0.

    All in all for that price, I have to admit that it’s a good, all purpose machine that you can easily use for your experiments and to learn new possibilities in computing.

    So the first thing I wanted to test is how this little machine would be able to stream GTK applications over the network using the Broadway back-end available in GTK+.

    After flashing Debian Jessie on it (that comes without and window manager), I had to compile GTK+ with the Broadway backend enabled (this is now standard in most i386 and amd64 distribution, but not in ARM ones), following the compiling instructions on the GTK+ page.

    So after logging into your C.H.I.P. you need to install the dependencies – some of them are already packaged in the right version, while you will have to compile others:

    sudo apt-get install pkg-config make autoconf2.13 libtool zlib1g-dev libffi-dev gettext libfam-dev libpackagekit-glib2-dev libgtk2.0-dev python2.7-dev gtk-doc-tools libglib2.0-dev gir1.2-glib-2.0 libtiff5-dev flex bison python-dev libcairo2-dev libepoxy-dev libatk-bridge2.0-dev vim libgirepository1.0-dev unzip

    then you will need to install GLIB:

    cd ~

    wget http://ftp.gnome.org/pub/gnome/sources/glib/2.46/glib-2.46.2.tar.xz

    tar xvfJ glib-2.46.2.tar.xz

    cd glib-2.46.2



    Now you need to find the path for giving the CFLAGS to make:

    pkg-config --cflags glib-2.0

    the path that will be shown will have to be used as the example below:

    make CFLAGS='-I/usr/include/glib-2.0 -I/usr/lib/arm-linux-gnueabihf/glib-2.0/include'

    make install

    export LD_LIBRARY_PATH="/usr/local/lib/:/usr/local/lib/pkgconfig"

    Now it’s time to compile pango, gobject-introspection, gdk-pixbuf, atk and finally GTK+

    cd ~

    wget http://ftp.gnome.org/pub/gnome/sources/pango/1.38/pango-1.38.1.tar.xz

    tar xvfJ pango-1.38.1.tar.xz

    cd pango-1.38.1




    make install

    cd ~

    wget http://ftp.gnome.org/pub/gnome/sources/gobject-introspection/1.46/gobject-introspection-1.46.0.tar.xz

    tar xvfJ gobject-introspection-1.46.0.tar.xz

    cd gobject-introspection-1.46.0



    make install

    cd ~

    wget http://ftp.gnome.org/pub/gnome/sources/gdk-pixbuf/2.32/gdk-pixbuf-2.32.3.tar.xz

    tar xvfJ gdk-pixbuf-2.32.3.tar.xz

    cd gdk-pixbuf-2.32.3



    make install

    cd ~

    wget http://ftp.gnome.org/pub/gnome/sources/atk/2.18/atk-2.18.0.tar.xz

    tar xvfJ atk-2.18.0.tar.xz

    cd atk-2.18.0



    make install

    cd ~

    wget http://ftp.gnome.org/pub/gnome/sources/gtk+/3.18/gtk+-3.18.6.tar.xz

    tar xvfJ gtk+-3.18.6.tar.xz

    cd gtk+-3.18.6

    ./autogen.sh --enable-broadway-backend --enable-x11-backend

    ./configure --enable-broadway-backend --enable-x11-backend


    make install

    The time to test the result of our creature has come:

    first of all enable the broadwayd deamon server and choose the port and screen to use:

    broadwayd -p 8080 :2 &

    export GDK_BACKEND=broadway

    export BROADWAY_DISPLAY=:2

    Finally, install a GTK application like shotwell, gedit or galculator

    sudo apt-get install gedit galculator shotwell

    and launch one of them…


    From another machine, now you can fire your browser and point to the address http://ipofyourc.h.i.p:8080

    and use your application running remotely from your browser.

    GEdit working in Chromium

  • Tutorial: boot Parallella from USB external hard drive (using standard SD image)

    I’ve been using my Parallella for a few months now and I’ve already burnt a couple of SD Cards…

    Therefore I thought that it would be better to load the OS from an USB attached Hard Disk, using the SD Card for the boot process only.

    Parallella Board

    In general Linux allows to easily change the root partition by passing the appropriate parameters to the Kernel (or through a bootloader). However in the standard image used by Parallella, a Device Tree is used. This means that you cannot pass directly the desired parameters to the Kernel, but you need modify the standard Device Tree. This is located in the Kernel package available at: http://www.parallella.org/create-sdcard/. See the point #2 (Parallella Linux Kernel – with ot without HDMI support, as you prefer) to download it.

    Once you have decompressed the content (as explained in the instructions), you will see that one of the files is called “devicetree.dtb”. The file is compiled so we’ll need to decompile it. On the Parallella, make a copy of the file in another folder and launch the command:

    dtc -I dtb -o dev.dts -O dts devicetree.dtb

    if the command cannot be found, just install it using:

    sudo apt-get install device-tree-compiler


    Now the file dev.dts is in text again and can be customized.

    Open the file with your favourite text editor and look for the line that begins with “bootargs”. In there you can specify any kernel boot options as described here.

    In our case, we want to boot from a USB attached drive. In order to do so, we need to use the instructions we saw before at Parallella site to copy the official image to an Hard Disk (CAUTION, YOU WILL DELETE YOUR HARD DISK CONTENT – YOU’VE BEEN WARNED!!!). It’s quite simple as you just need to adapt the command to create the partitions by using the appropriate /dev/sdxx device that is related to your external hard disk.


    Therefore the bootargs line will have to look like:

    bootargs = "rootwait root=/dev/sda2 rw rootfstype=ext4";


    Finally, re-compile the new Device Tree:

    dtc -I dts -O dtb -o devicetree.dtb dev.dts

    And now overwrite the old Device Tree with the new one. Happy OS loading from USB!

  • Tutorial: How to mount raw images (.img) images on Linux

    If you have a few .img files coming as disk images from devices like floppies, CDs, DVDs, SD cards, etc, you will realize that  you cannot mount the in Linux, because they contain a file system that has to be mounted.

    In linux you would need to use the mount command as for any physical device, however you need to know the correct syntax that is based on understanding the information related to the partition(s) available in the image.

    First step is to read the partition Start point using fdisk:

    In the terminal type:

    sudo fdisk -l imgfile.img

    You will see an output similar to the one below:
    Device        boot    Start     End         Blocks      Id  System
    imgfile.img1      *             63           266544          722233           C     W95 FAT32 (LBA)
    imgfile.img2                   25679      25367890        245667890+      83    Linux

    As you can see there are two partitions, one that is FAT32 and the other one that it’s ExtFS. This means that to mount the first partition we have to tell Linux that we need to start at the sector 63. The standard sector size is 512 bytes, however there are other possibilities like 128 or 1024. Assuming that the place from where you are downloading the image doesn’t specify any sector size, we can type in the terminal:

    sudo mount -t vfat -o loop,offset=$((63 * 512)) imgfile.img /mnt/disk

    To mount the second partition, as you can imagine:

    mount -t ext4 -o loop,offset=$((25679 * 512)) imgfile.img /mnt/disk1

    It’s important to copy the “Start” sector number correctly, otherwise you’ll get an error message like:

    mount : wrong fs type, bad option, band superblock on /dev/loop,
    missing codepage or helper proggram, or other error
    In some cases useful info is found in syslog – try
    dmesg | tail or so

    One last thing, the standard sector size for CDs and DVDs is 2352 instead of 512. If you are opening such image, you’ll have to use this value instead of 512.

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