PowerVR Neural Network SDK

Chromebook installation instructions

Installing the Chromebook Image

We have created an image that developers can flash to an Acer Chromebook R-13 which has a PowerVR GX6250 GPU. This image will install a version of Linux (Arch Linux) along with the Neural Network SDK and demos on a SD card. As there are currently no consumer platforms that support CLDNN natively as it requires our v1.9 drivers, this image is essential. It allows developers to get access to everything they need to write Neural Network applications on an easy to use device with a built-in webcam.

PowerVR CLDNN Chromebook Image

Installation Instructions

There are two installation options available to developers:

  • A bootable MicroSD, which will keep the stock ChromeOS intact. This will create a dual-boot environment where you can easily switch between booting either Arch Linux or the stock ChromeOS. The internal eMMC storage device will remain untouched and the Arch Linux image will run completely from the external storage device. This is the recommended setup for those that just want to take a test drive, or don’t want to give up ChromeOS.
  • Install the Arch Linux image directly to the device. This will erase the ChromeOS entirely from the internal storage. This will permanently remove the stock ChromeOS and any user data held on the device.

Note that before starting installation you must be running the latest ChromeOS.

1. Install image on a MicroSD

  1. Download and extract the Chromebook package onto your Linux developer machine. After extracting you should have two files: flash_arch_image.sh and ArchLinuxARM-oak-latest_IMG_DDK_1.9_RTM.tar.gz.
  2. To create the flash drive both cgpt and parted must be installed on your developer machine. For Ubuntu users these packages can be installed by executing the following command: sudo apt-get install cgpt parted
  3. Plug your MicroSD into your developer machine via the card reader.
  4. Execute the flash_arch_image script. Note that you may need to allow execute permisions on the file and execute as root.
  5. Choose which device to flash the Chromebook image onto – pick very carefully – make sure you select your MicroSD drive. Tip – look for the device that is the same size as your MicroSD.
    $ sudo ./flash_arch_image.sh
    $ This script will flash a working ChromeOS image onto the chosen device.
    $ (0) sda: 465.8G
    $ (1) sdb: 465.8G
    $ (2) sdc: 3.8G
    $ Please select the device to flash: 2
  6. Confirm your choice before flashing the image to the chosen device – choose y or N.
    $ WARNING: This will format /dev/sdc, continue [y/N]? y
  7. $ Device hostname (arch-linux-chromebook): myChromebook
  8. The procedure can take around 10-15 minutes, once complete you will have a bootable MicroSD card, running Arch Linux.

Whilst waiting for the bootable MicroSD card to finish being created, the Chromebook can be set up.

2. Switch to developer mode

  1. Turn off the Chromebook.
  2. Invoke recovery mode, by holding down the ESC and Refresh (the key fourth from the left on the top row) keys at the same time and then hitting the Power button.
  3. At the Recovery screen press Ctrl+D. Note: there is no prompt – you have to know to do it.
  4. Confirm switching to developer mode (“Turn OS verification off”) by pressing ENTER, and the laptop will reboot and reset the system. This takes about 10-15 minutes.

Note: After enabling developer mode, you will need to press Ctrl+D to boot from the internal storage device every time you power on or restart the laptop.

3. Enable booting from external storage

  1. After booting into developer mode, skip logon and enter as a guest. Hold Ctrl+Alt and hit the T key. This will open up the crosh shell in a new tab in Chrome.
  2. Type the command shell to get into a bash shell.
  3. Type the command sudo su to become root user.
  4. Enable USB booting by typing the following command: $ crossystem dev_boot_usb=1 dev_boot_signed_only=0
  5. Reboot the system to allow the change to take effect.

4. Ready to go

Plug the MicroSD card into the Chromebook, switch on the device and hit CTRL+U to boot from the external device. If the Chromebook is not connected to a network, you will have to wait 90 seconds, this is normal.

The default username and password is root.

Alternatively – installing the image onto the internal eMMC storage device

If you want the image permanently on the R-13, you will need to do the following. Please note this will permanently erase ChromeOS from the internal eMMC.

  1. Follow the steps to create a bootable MicroSD (above).
  2. Copy the Chromebook image and flash script to the MicroSD card.
  3. Boot the Chromebook from the MicroSD (CTRL+U).
  4. Execute the flash_arch_image  script.
  5. This time the script will detect that you are running on a Chromebook and will ask you if you would like to flash the Chromebook’s internal storage. Select Y to erase ChromeOS and install Arch Linux: $ Chromebook detected! Would you like to use this device [Y/n]: Y
  6. Choose a hostname for the device.
  7. Once the procedure is complete reboot the device and hit CTRL+D to boot from the internal storage device. The default username and password is root.

Support & resources

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