Installing OpenCL on Chromebook in 30 minutes

I am interrupting my blog series to share what I think is a rather elegant way to quickly get up and running with OpenCL on the ARM® Mali-T604 GPU powered Chromebook. 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, 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 30 MB/s and 45 MB/s cards). The basic OpenCL installation should take up to half an hour; PyOpenCL and NumPy about an hour; further SciPy libraries about 3-4 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 Mon Jan 19 21:52:05 PST 2015 armv7l SAMSUNG EXYNOS5 (Flattened Device Tree) GNU/Linux

Preparing an SD card (5 min)

Insert a blank SD card (denoted as /dev/mmcblk1 in what follows). Unmount the card and run fdisk:

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

Welcome to fdisk (util-linux 2.25.1).
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 '15' 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): 15
Changed type of partition 'Microsoft basic data' to 'Linux filesystem'.

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

NB: In earlier versions of fdisk (e.g. 2.24), the Linux partition type is '83'.

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 (10-15 min)

chronos@localhost / $ cd ~/gentoo
chronos@localhost ~/gentoo $ ls -la
total 32
drwxr-xr-x  3 root    root            4096 Jan 23 14:25 .
drwx--x--- 29 chronos chronos-access 12288 Jan 23 14:28 ..
drwx------  2 root    root           16384 Jan 23 14:25 lost+found

Download the latest stage 3 archive for armv7a_hardfp:

chronos@localhost ~/gentoo $ sudo wget http://distfiles.gentoo.org/releases/arm/autobuilds/latest-stage3-armv7a_hardfp.txt
chronos@localhost ~/gentoo $ sudo wget http://distfiles.gentoo.org/releases/arm/autobuilds/`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-T60x Linux drivers and download mali-t604_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-t604_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/setup.sh
#!/bin/sh
GENTOO_DIR=/home/chronos/user/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/enter.sh
#!/bin/sh
GENTOO_DIR=/home/chronos/user/gentoo
LC_ALL=C chroot $GENTOO_DIR /bin/bash
chronos@localhost ~/gentoo $ sudo chmod u+x ~/gentoo/setup.sh ~/gentoo/enter.sh

Execute the scripts:

chronos@localhost ~/gentoo $ sudo ~/gentoo/setup.sh
chronos@localhost ~/gentoo $ sudo ~/gentoo/enter.sh
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 http://www.khronos.org/registry/cl/api/1.1/opencl.h
localhost / # wget http://www.khronos.org/registry/cl/api/1.1/cl_platform.h
localhost / # wget http://www.khronos.org/registry/cl/api/1.1/cl.h
localhost / # wget http://www.khronos.org/registry/cl/api/1.1/cl_gl.h
localhost / # wget http://www.khronos.org/registry/cl/api/1.1/cl_ext.h

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

Summary

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/setup.sh

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

chronos@localhost / $ sudo ~/gentoo/enter.sh
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=\"-j2\"" >> /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
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 (30-40 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 --autounmask-write dev-python/numpy
localhost / # python -c "import numpy; print numpy.__version__"
1.9.1

Installing PyOpenCL (5-10 min)

Install PyOpenCL.

localhost / # cd /tmp
localhost tmp # wget https://pypi.python.org/packages/source/p/pyopencl/pyopencl-2014.1.tar.gz
localhost tmp # tar xvzf pyopencl-2014.1.tar.gz
localhost tmp # cd pyopencl-2014.1
localhost pyopencl-2014.1 # python configure.py
localhost pyopencl-2014.1 # make install
localhost pyopencl-2014.1 # cd examples
localhost examples # python demo.py
(0.0, 241.63054)
localhost examples # python -c "import pyopencl; print pyopencl.VERSION_TEXT"
2014.1

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 (30-45 min)

localhost / # emerge --autounmask-write dev-python/ipython
localhost / # ipython --version
1.2.1

Installing IPython Notebook (3-7 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: http://cdn.mathjax.org/mathjax/latest/MathJax.js
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: http://127.0.0.1:8888/
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 http://127.0.0.1:8888/ in a new Chrome tab to start creating your own IPython Notebooks!

Installing Matplotlib (35-50 min)

localhost / # emerge --autounmask-write dev-python/matplotlib
localhost / # python -c "import matplotlib; print matplotlib.__version__"
1.4.0

Installing SciPy (45-60 min)

localhost / # emerge --autounmask-write sci-libs/scipy
localhost / # python -c "import scipy; print scipy.__version__"
0.14.0

Installing Pandas (55-80 min)

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
localhost / # python -c "import pandas; print pandas.__version__"
0.14.1
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