Installing OpenCL on Chromebook 2 in 30 minutes

I have previously shared how to install OpenCL on the Samsung XE303C12 Chromebook powered by the ARM® Mali-T604 GPU. I have found that things are slightly different on the newer Samsung XE503C12 Chromebook ("Chromebook 2") powered by the ARM® Mali-T628 GPU, so decided to provide an update. As before, please bear in mind that this is not ARM's "official guide" (which can be found here). However, it's a useful alternative to the official guide if, for example, you don't have a Linux PC or just want to use Chrome OS day in and day out.

You will need:

How fast you will complete the installation will depend on how fast you can copy-and-paste instructions from this guide (Ctrl-C) into the shell (Shift-Ctrl-C), how fast your Internet connection is and how fast your memory card is. (I will give an approximate time for each step measured when using a rather slow 30 MB/s card). The basic OpenCL installation should take up to half an hour; PyOpenCL and NumPy about an hour; further SciPy libraries about 4 hours. Most of the time, however, you will be able to leave the Chromebook unattended, beavering away while compiling packages from source.

Finally, the instructions are provided "as is", you use them at your own risk, and so on, and so forth... (The official guide also contains an important disclaimer.)

Installing OpenCL

Enabling Developer Mode

NB: Enabling Developer Mode erases all user data - do a back up first.

Enter Recovery Mode by holding the ESC and REFRESH (↻ or F3) buttons, and pressing the POWER button. In Recovery Mode, press Ctrl+D and ENTER to confirm and enable Developer Mode.

Entering developer shell (1 min)

Open the Chrome browser and press Ctrl-Alt-T.

Welcome to crosh, the Chrome OS developer shell.

If you got here by mistake, don't panic!  Just close this tab and carry on.

Type 'help' for a list of commands.

Don't panic, keep the tab opened and carry on to enter the shell:

crosh> shell
chronos@localhost / $ uname -a
Linux localhost 3.8.11 #1 SMP Wed Dec 10 14:41:54 PST 2014 armv7l SAMSUNG EXYNOS5 (Flattened Device Tree) GNU/Linux

Preparing a Micro SD card (5 min)

Insert a blank Micro SD card (denoted as /dev/mmcblk1 in what follows):

chronos@localhost / $ mount | grep "SD Card"
/dev/mmcblk1p1 on /media/removable/SD Card type vfat (rw,nosuid,nodev,noexec,relatime,dirsync,uid=1000,gid=1000,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,utf8,flush,errors=remount-ro)

Unmount the card and run fdisk:

chronos@localhost / $ sudo umount /dev/mmcblk1p1
chronos@localhost / $ sudo /sbin/fdisk /dev/mmcblk1

Welcome to fdisk (util-linux 2.24).
Changes will remain in memory only, until you decide to write them. Be careful before using the write command. Command (m for help):

Enter 't' to change a partition type, then '83' to change the partition type to 'Linux', and finally 'w' to apply the change:

Command (m for help): t
Selected partition 1
Hex code (type L to list all codes): 83
If you have created or modified any DOS 6.x partitions, please see the fdisk documentation for additional information.
Changed type of partition 'W95 FAT32 (LBA)' to 'Linux'.

Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.
chronos@localhost / $ 

Format the card e.g. using ext3:

chronos@localhost / $ sudo /sbin/mkfs.ext3 /dev/mmcblk1p1

NB: If you use a card that is less than 8 GB, you may need to reserve enough inodes when you format the card e.g.:

chronos@localhost / $ sudo /sbin/mkfs.ext3 /dev/mmcblk1p1 -j -T small

Mount the card and check that it's ready:

chronos@localhost / $ sudo mkdir -p ~/gentoo
chronos@localhost / $ sudo mount -o rw,exec -t ext3 /dev/mmcblk1p1 ~/gentoo
chronos@localhost / $ df -h ~/gentoo
Filesystem      Size  Used Avail Use% Mounted on
/dev/mmcblk1p1   15G   38M   14G   1% /home/chronos/user/gentoo
chronos@localhost / $ df -hi ~/gentoo
Filesystem     Inodes IUsed IFree IUse% Mounted on
/dev/mmcblk1p1   951K    11  951K    1% /home/chronos/user/gentoo

Installing Gentoo Linux (15 min)

chronos@localhost / $ cd ~/gentoo
chronos@localhost ~/gentoo $ ls -la
total 32
drwxr-xr-x  3 root    root            4096 Dec  9 21:31 .
drwx--x--- 30 chronos chronos-access 12288 Dec  9 21:38 ..
drwx------  2 root    root           16384 Dec  9 21:31 lost+found

Download the latest stage 3 archive for armv7a_hardfp:

chronos@localhost ~/gentoo $ sudo wget
chronos@localhost ~/gentoo $ sudo wget`cat latest-stage3-armv7a_hardfp.txt | grep stage3-armv7a_hardfp`

Extract the downloaded archive right onto the card e.g.:

chronos@localhost ~/gentoo $ sudo tar xjpf stage3-armv7a_hardfp-20141023.tar.bz2

Clean up:

chronos@localhost ~/gentoo $ sudo rm latest-stage3-armv7a_hardfp.txt
chronos@localhost ~/gentoo $ sudo rm stage3-armv7a_hardfp-20141023.tar.bz2

Downloading OpenCL drivers (4 min)

Go to the page listing Mali-T6xx Linux drivers and download release r4p0-02rel0 for Mali-T62x fbdev (mali-t62x_r4p0-02rel0_linux_1+fbdev.tar.gz). Make sure you carefully read and accept the associated licence terms.

chronos@localhost ~/gentoo $ sudo tar xvzf ~/Downloads/mali-t62x_r4p0-02rel0_linux_1+fbdev.tar.gz 

This will create ~/gentoo/fbdev which we will use later.

Entering Gentoo Linux (2 min)

Similar to crouton, we will use chroot to enter our Linux environment.

Create two scripts and make them executable:

chronos@localhost ~/gentoo $ sudo vim ~/gentoo/
mount -t proc /proc $GENTOO_DIR/proc
mount --rbind /sys  $GENTOO_DIR/sys
mount --rbind /dev  $GENTOO_DIR/dev
cp /etc/resolv.conf $GENTOO_DIR/etc
chronos@localhost ~/gentoo $ sudo vim ~/gentoo/
LC_ALL=C chroot $GENTOO_DIR /bin/bash
chronos@localhost ~/gentoo $ sudo chmod u+x ~/gentoo/ ~/gentoo/

Execute the scripts:

chronos@localhost ~/gentoo $ sudo ~/gentoo/
chronos@localhost ~/gentoo $ sudo ~/gentoo/
localhost / # 

Note that the ~/gentoo directory will become the root (/) directory once we enter our new Linux environment. For example, ~/gentoo/fbdev will become /fbdev inside the Linux environment.

Installing OpenCL header files (2 min)

Download OpenCL header files from the Khronos OpenCL registry:

localhost / # mkdir /usr/include/CL && cd /usr/include/CL
localhost / # wget
localhost / # wget
localhost / # wget
localhost / # wget
localhost / # wget

Installing OpenCL driver (2 min)

Change properties on the downloaded OpenCL driver files and copy them to /usr/lib:

localhost / # chown root /fbdev/*
localhost / # chgrp root /fbdev/*
localhost / # chmod 755 /fbdev/*
localhost / # mv /fbdev/* /usr/lib
localhost / # rmdir /fbdev


By now you should have a mint Linux installation complete with the OpenCL drivers and headers, so you can start playing with OpenCL!

When you reboot, you just need to mount the card and execute the setup script again:

chronos@localhost / $ sudo mount -o rw,exec -t ext3 /dev/mmcblk1p1 ~/gentoo
chronos@localhost / $ sudo ~/gentoo/

Then you can pop in and out of the Linux environment with:

chronos@localhost / $ sudo ~/gentoo/
localhost / # exit
chronos@localhost / $

But the fun just begins here! Follow the instructions below to install PyOpenCL and SciPy libraries for scientific computing.

Installing PyOpenCL

Configuring Portage (15 min)

Portage is Gentoo's package management system.

localhost / # echo "MAKEOPTS=\"-j4\"" >> /etc/portage/make.conf
localhost / # echo "ACCEPT_KEYWORDS=\"~arm\"" >> /etc/portage/make.conf
localhost / # mkdir /etc/portage/profile
localhost / # mkdir /etc/portage/package.use
localhost / # mkdir /etc/portage/package.unmask
localhost / # mkdir /etc/portage/package.accept_keywords
localhost / # mkdir /etc/portage/package.keywords
localhost / # touch /etc/portage/package.keywords/dependences

Perform an update:

localhost / # emerge --sync --quiet
localhost / # emerge --oneshot portage
localhost / # eselect news read

NB: If any emerge command below fails, rerun it with the --autounmask-write flag; then run etc-update and answer '-3' followed by 'y'. Running emerge again should now get the build started e.g.:

localhost / # emerge --autounmask-write dev-python/pandas
localhost / # etc-update
Scanning Configuration files...
The following is the list of files which need updating, each
configuration file is followed by a list of possible replacement files.
1) /etc/portage/package.keywords/dependences (1)
Please select a file to edit by entering the corresponding number.
              (don't use -3, -5, -7 or -9 if you're unsure what to do)
              (-1 to exit) (-3 to auto merge all files)
                           (-5 to auto-merge AND not use 'mv -i')
                           (-7 to discard all updates)
                           (-9 to discard all updates AND not use 'rm -i'): -3
Replacing /etc/portage/package.keywords/dependences with /etc/portage/package.keywords/._cfg0000_dependences
mv: overwrite '/etc/portage/package.keywords/dependences'? y
Exiting: Nothing left to do; exiting.
localhost / # emerge dev-python/pandas

Setting up Python (3 min)

localhost / # eselect python set python2.7
localhost / # emerge dev-python/setuptools

Installing NumPy (40 min)

Install NumPy with LAPACK as follows.

localhost / # echo "dev-python/numpy lapack" >> /etc/portage/package.use/numpy
localhost / # echo "dev-python/numpy -lapack" >> /etc/portage/profile/package.use.mask
localhost / # emerge dev-python/numpy
localhost / # python -c "import numpy; print numpy.__version__"

Installing PyOpenCL (7 min)

Install PyOpenCL.

localhost / # cd /tmp
localhost tmp # wget
localhost tmp # tar xzf pyopencl-2014.1.tar.gz
localhost tmp # cd pyopencl-2014.1
localhost pyopencl-2014.1 # python
localhost pyopencl-2014.1 # make install
localhost pyopencl-2014.1 # cd examples
localhost examples # python
Choose device(s):
[0] <pyopencl.Device 'Mali-T628' on 'ARM Platform' at 0x-49b96370>
[1] <pyopencl.Device 'Mali-T628' on 'ARM Platform' at 0x-49b96270>
Choice, comma-separated [0]:0
Set the environment variable PYOPENCL_CTX='0' to avoid being asked again.
(0.0, 241.52145)
localhost examples # python -c "import pyopencl; print pyopencl.VERSION_TEXT"

(That's right! The Exynos 5420 chip effectively has two Mali-T62x GPUs: GPU 0 has 4 cores; GPU 1 has 2 cores. How cool is that?)

Installing scientific libraries

If you would like to follow my posts on benchmarking (e.g. see the intro), I recommend you install packages from the SciPy family.

Installing IPython (45 min)

localhost / # emerge dev-python/ipython
localhost / # ipython --version

Installing IPython Notebook (5 min)

Install IPython Notebook to enjoy a fun blend of Chrome OS and IPython experience.

localhost / # emerge dev-python/jinja dev-python/pyzmq www-servers/tornado
localhost / # ipython notebook
2014-05-08 06:49:08.424 [NotebookApp] Using existing profile dir: u'/root/.ipython/profile_default'
2014-05-08 06:49:08.440 [NotebookApp] Using MathJax from CDN:
2014-05-08 06:49:08.485 [NotebookApp] Serving notebooks from local directory: /
2014-05-08 06:49:08.485 [NotebookApp] The IPython Notebook is running at:
2014-05-08 06:49:08.486 [NotebookApp] Use Control-C to stop this server and shut down all kernels (twice to skip confirmation).
2014-05-08 06:49:08.486 [NotebookApp] WARNING | No web browser found: could not locate runnable browser.

Open in a new Chrome tab to start creating your own IPython Notebooks!

Installing Matplotlib (50 min)

localhost / # emerge dev-python/matplotlib
localhost / # python -c "import matplotlib; print matplotlib.__version__"

Installing SciPy (60 min)

localhost / # emerge sci-libs/scipy
localhost / # python -c "import scipy; print scipy.__version__"

Installing Pandas (80 min)

localhost / # emerge dev-python/pandas
localhost / # python -c "import pandas; print pandas.__version__"