oldjohn86 / ubuntu-rt-up-board

The RT-PREEMPT 4.4 kernel of ubuntu for UP board.

Ubuntu-RT-UP-Board

An UP board Ubuntu real-time patched kernel (4.4.86).

Grab & Go!

Here's a compiled image for UP Board. Copy and paste following in your terminal:

wget -c "https://github.com/QiayuanLiao/Ubuntu-RT-UP-Board/releases/download/UP-board-4.4.86-rt99/UP-board-4.4.86-rt99.tar.xz" && tar -xvzf UP-board-4.4.86-rt99.tar.xz

You are all set now! For the next step:

1. If you need help to replace the kernel or install Ubuntu, please follow the link and read on.
2. To test this kernel please refer to Configuration and Test
3. Also if you want to build from source, here is the tutorial.
4. Finally, here's a step by step tutorial to build from generic kernel

Features

• The UP board patches is modify from this repo to work with kernel version 4.4.86
• Supported Buses:
  • GPIO
  • UART
  • SPI
  • I2C
  • LEDs
• Unsupported:
  • HDMI Audio
  • PWM(frequency error)

Help Desk

Replace the kernel

1. Copy the Debian packages to UP board

2. Remove all the generic installed kernel

   sudo apt-get autoremove --purge 'linux-.*generic'
   

3. Go to the file of debian packages and install the kernel:

   sudo dpkg -i linux-*.deb
   

4. Reboot

   sudo reboot
   

5. Verify that the kernel is indeed installed by typing

   uname -v
   

   you should get

   #1 SMP PREEMPT RT xxxxxxxx
   

Install Ubuntu

1. Download Ubuntu 16.04.6 ISO from the Ubuntu download page (works with desktop and server edition)

   http://releases.ubuntu.com/16.04/ubuntu-16.04.6-desktop-amd64.iso http://releases.ubuntu.com/16.04/ubuntu-16.04.6-server-amd64.iso

2. Burn the downloaded image on a USB stick. We suggest to use etcher for doing that. You can download it from:

   https://etcher.io

3. Insert the USB thumb drive in a empty USB port and proceed with a normal Ubuntu installation.

Build from source

1. Get the source:

   git clone [email protected]:QiayuanLiao/Ubuntu-RT-UP-Board.git
   cd Ubuntu-RT-UP-Board
   

2. Config the kernel:

   cp .config kernel
   cd kernel
   make menuconfig
   

   selet save and exit

3. Make the kernel

   make -j`nproc` && make -j`nproc` bindeb-pk
   

   Then you will get:

   linux-firmware-image-4.4.86-rt99_4.4.86-rt99-1_amd64.deb
   linux-headers-4.4.86-rt99_4.4.86-rt99-1_amd64.deb
   linux-image-4.4.86-rt99_4.4.86-rt99-1_amd64.deb
   linux-libc-dev_4.4.86-rt99-1_amd64.deb
   

Build from generic kernel step by step

1. Get kernel from:

   https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/snapshot/linux-4.4.86.tar.gz
   

   and decompress.

2. Get RT_PREEMPT patch from:

   https://mirrors.edge.kernel.org/pub/linux/kernel/projects/rt/4.4/older/patches-4.4.86-rt99.tar.xz

3. Get UP board patches from release

   https://github.com/QiayuanLiao/Ubuntu-RT-UP-Board/releases/download/UP-board-4.4.86-rt99/UP-borad-patches.tar.xz

4. Copy patches-4.4.86-rt99.tar.xz to linux-4.4.86, then patch:

   unxz -cd patches-4.4.86-rt99.tar.xz | patch -p1
   

5. Copy UP-borad-patches.tar.xz to linux-4.4.86, then patch:

   unxz -cd UP-borad-patches.tar.xz | patch -p1
   

6. Config and make

Configuration and Test

Config and test HAT device

1. Check if there are two SPI device

   ls /dev/spidev*
   

   you should get:

   /dev/spidev2.0  /dev/spidev2.1
   

2. Enable the HAT functionality from userspace

   sudo add-apt-repository ppa:ubilinux/up
   sudo apt install upboard-extras
   sudo usermod -a -G gpio ${USER}
   sudo usermod -a -G leds ${USER}
   sudo usermod -a -G spi ${USER}
   sudo usermod -a -G i2c ${USER}
   sudo usermod -a -G dialout ${USER}
   sudo reboot
   

3. Go to the /test file run the ./blink.sh

   cd test
   sh ./blink.sh
   

   then the green led of UP board will blink

4. For HAT test, check

   https://wiki.up-community.org/Pinou

Real time test using latency plot under the stress

1. Install requirement

   sudo apt install rt-tests stress gnuplot
   

2. Go to the /test file and Run the RT test

   cd test
   sudo sh  ./rt-test.sh
   

   The latency plot look like this:

   

3. Analysis:

   • More sample on the left means lower latency in general
   • More clustered samples indicate less flutter
   • The max latency should not deviate far from mean value (typically under 100us)

Credits

@dicarlo236 helped a lot through out patching work.