How to get LinuxCNC running on a RPi

View the Project on GitHub scottalford75/LinuxCNC-on-RPi

LinuxCNC install on Arch Linux - Raspberry Pi

LinuxCNC development and installation instructions are Debian based. Therefore building LinuxCNC on Raspbian Stretch is reasonably straightforward as we are working in a Debian based distribution.

Why Arch Linux then you may ask? Well, Raspbian Stretch worked great for an out of the box LinuxCNC build, but once I wanted to use QtPyVCP to develop a custom 3D printer UI I soon found that the stable release model would not work correctly due to older OpenGL libraries.

Therefore, the search was on to find a distribution that would give this functionality on the Raspberry Pi. All the Debian based distros appeared to have the same problem. Arch Linux looked to be an option and pleasingly a fully functional Raspberry Pi 3 with LinuxCNC and QtPyVCP was the result.

To install Arch Linux

Arch Linux is a lightweight Linux distribution with rolling updates. Unlike Raspbian there is no prepared SD card image available so the initial installation is a little more involved. There is good installation instruction of the Arch Linux Arm site:

TODO – script use to create an image. This script also needs bsdtar, kpartx, and parted.

Once the base system is installed we need to get everything setup ready to install LinuxCNC, Qt5 and PyQT5.

STEP 1: Get onboard Wifi up and running

Later we will setup Network Manager but initially we will configure wpa_supplicant to get the Wifi interface wlan0 up and running.

$ cd /etc/wpa_supplicant/  
$ nano homenetwork`
    ssid=“your ssid”  
    psk=“your pass code”    

Start up the Wifi by specifying the interface, wlan0, and the configuration file we just created above.

$ wpa_supplicant –iwlan0 –c /etc/wpa_supplicant/homenetwork &

Manually start the DHCP daemon on the wireless interface.

$ dhcpcd wlan0

STEP 2: Update the system

Now that the network is up, we can update the system.

$ pacman-key –-init
$ pacman-key --populate archlinuxarm
$ pacman -Syu

STEP 3: Set user “alarm” as super user

Firstly, we need to install the sudo package.

$ pacman -S sudo

The default user is “alarm” so we need to setup super user privileges.

$ cd /etc/sudoers.d/
$ nano myOverrides

For the remainder of the installation we will switch over to the default user “alarm”

$ su alarm

STEP 4: Install X11 and desktop environment

Install X11 and the Xfce desktop environment.

$ sudo pacman –S xorg-server xf86-video-fbdev xorg-xrefresh
$ sudo pacman –S xfce4

If you want to keep a lightweight environment, you may want to skip the following and only install the utility software that you will need later.

$ sudo pacman –S xfce4-goodies

If not using a session manager, install xorg-xinit.

exec startxfce4

STEP 5: Install session manager

Install a session manager. We will use SDDM (Simple Desktop Display Manager).

$ sudo pacman –S sddm
$ sudo sh –c “sddm --example-config > /etc/sddm.conf”
$ sudo systemctl enable sddm
$ sudo systemctl start sddm

Alternatively we can use lightdm.

$ sudo pacman -S lightdm lightdm-gtk-greater
$ sudo systemctl enable lightdm
$ sudo systemctl start lightdm

You should now be ready to login to the desktop environment. User “alarm” with password “alarm”.

STEP 6: Install Network Manager

Open a terminal, install Network Manager, and start it.

$ sudo pacman –S networkmanager network-manager-applet
$ sudo systemctl enable NetworkManager
$ sudo systemctl start NetworkManager

In the top right hand of the screen, you will now have access to wired and wireless network configuration.

STEP 7: Install development tools

Install some tools to enable compiling etc

$ sudo pacman –S make gcc git-core automake autoconf pkg-config
$ sudo pacman –S libtool binutils patch

STEP 8: Install a desktop theme

If you like, you can install a desktop theme. For a nice dark theme, try ARC

$ sudo pacman –S arc-gtk-theme

STEP 9: Enable auto mounting of USB media

It is handy to be able to auto mount USB media rather than having to sudo mount all the time. With Thunar file manager installed we can add the thunar-volman plugin. However, this did not appear to be available for armv7h so had to be built from source.

thunar-volman now appears to be in the repos…

Several other packages are also needed as well.

$ sudo pacman –S autofs gvfs udisks2 ntfs-3g

STEP 10: Install Python 2

We only want to install Python2 at this stage. With both Python 2 and 3 installed in the system, I had issues getting PyQt5 to make the correct plugin module.

As a note, avoid using Pip to install Python packages! Pacman and Pip don’t seem to play well together.

$ sudo pacman –S python2

To install TigerVNC

Accessing the Raspberry Pi from another computer is an easy way to use the Pi. The Virtual Network Computing (VNC) protocol will be used with the TigerVNC package.

$ sudo pacman –S tigervnc

Create environment, config, and password files

The first time vncserver is run, it creates its initial environment, config, and user password file. These will be stored in ~/.vnc, which will be created if not present.

$ vncserver
You will require a password to access your desktops.


New 'alarmpi:1 (facade)' desktop is alarmpi:1

Creating default startup script /home/alarm/.vnc/xstartup
Starting applications specified in /home/alarm/.vnc/xstartup
Log file is /home/alarm/.vnc/alarmpi:1.log

We will use “System mode” to start the VNC server as required on the headless system.

Create /etc/systemd/system/vncserver@:1.service, where :1 is the 5900 port increment (5900 + 1) to which the VNC server will be listening for connections (e.g vncserver@:5.service means the server will be listening to port 5905). Edit the service unit by defining the user (User=) to run the server, and the desired Vncserver options.

$ sudo nano /etc/systemd/system/vncserver@:1.service

Description=Remote desktop service (VNC)

ExecStartPre=/bin/sh -c '/usr/bin/vncserver -kill %i > /dev/null 2>&1 || :'
ExecStart=/usr/bin/vncserver %i -geometry 1440x900 -alwaysshared -fg
ExecStop=/usr/bin/vncserver -kill %i


Start and enable the service to rat at boot time / shutdown.

$ sudo systemctl enable vncserver@:1.service
$ sudo systemctl start vncserver@:1.service

We also need to setup TigerVNC to start our desktop environment when we connect remotely. Modify /home/alarm/.vnc/xstartup to read:


exec dbus-launch startxfce4

The Raspberry Pi can now be accessed via a VNC client using alarmpi:1 as the VNC server to connect to.

To install LinuxCNC

In the Arch Linux AUR (Arch User Repository) there is a package LinuxCNC-sim. This will build a “uspace” version of LinuxCNC into a package for installation. The dependencies and steps in the PKGBUILD were used as a starting point to build a run-in-place installation of LinuxCNC.

STEP 1: Install dependencies

Unfortunately there are not armv7h versions of all required dependencies available so we will need to build and install these first.

Arch Linux dependencies needed by LinuxCNC:

Package Repo Install PKGBUILD
intltool Yes  
bc Yes  
bwidget   Build
tcllib   Build
tclx   Build
tcl Yes  
tk Yes  
xorg-server Yes  
python2-imaging Yes  
tkimg   Build
tclx   Build
boost Yes  
boost-libs Yes  
libtirpc Yes  
procps-ng Yes  
psmisc Yes  

The fakeroot package is needed to build Arch Linux packages from a PKGBUILD.

$ sudo pacman –S fakeroot

New versions of LinuxCNC no longer include yapps in the source. Therefore, we need to install it in the system. However, Arch Linux does not seem to have a repo for this. I have included a Yapps source in the repository


In the above python file make sure that it is pointing at python 2. The first line should read


The following yapps directory in site-packages must include the files listed.


STEP 2: Get LinuxCNC source files

You need to have git installed and configured. Then

$ git clone linuxcnc-dev
$ cd linuxcnc-dev

STEP 3: Fix Python 2 naming

Arch Linux explicitly names both Python 2 and Python 3, whereas Debian systems use the Python and Python 3 naming convention. The following command will find the required files and change python to python2 within them.

$ find . -iname -o -iname checkglade -o -iname update_ini|xargs perl -p -i -e "s/python/python2/"

Note: run this command only once other wise you will end up with python22, python222 etc, and the compile will fail.

STEP 4: Apply libtirpc patch

The makefile needs a patch applied so that the make will succeed on Arch Linux. Copy libtirpc.patch into the LinuxCNC /src directory and execute the following command.

$ patch -Np2 -i libtirpc.patch

STEP 5: Run the autogen scripts

$ ./

STEP 6: Run the configuration script

Run the configuration script with the following parameters. Note, if you need libmodbus this dependency can be installed. For armv7h this will need to be built from source.

$ ./configure --with-realtime=uspace --without-libmodbus --with-python=/usr/bin/python2.7 --enable-non-distributable=yes

The script should complete without errors.

STEP 7: Compile LinuxCNC

$ make

STEP 8: Set permissions

As we will be running a real machine, we need to setup the required permissions.

$ sudo make setuid

STEP 9: Run LinuxCNC

LinuxCNC should now be ready to use as run-in-place (RIP).

$ . ./scripts/rip-environment
$ linuxcnc

Linuxcnc should load and be able to open Axis or other non-Qt user interfaces. A RT-Preempt kernel needs to be installed before being able to run a real machine.