Using Docker with Petalinux

How to run Petalinux on a non-supported Linux distro without a VM. Docker is similar to a virtual machine in many respects, but much lighter and faster, and having a reproducible environment to run Petalinux may be of useful when switching versions.

Overview

Docker can be used, among other things, to create a cross-compile environment to build hardware on a platform where the Petalinux tools may not be compatible or supported by Xilinx. In my case, Fedora 28 has some issues with Petalinux that made me look for a supported alternative.

Docker is built from a base file called Dockerfile, that has instructions what OS to build and post-configuration steps such as dependency packages, user permissions, etc.

This build that I’m working with is based on CentOS 7.4, the latest version supported by Petalinux. Starting with the stock CentOS, there’s a few packages that were added, like VNC server (tigervnc-server) and Xfce desktop for Vivado tools.

Volumes

Being a pseudo-virtual machine means storage is used by Docker, and these software packages are very big, making the resulting image potentially huge. A strategy I’m using is to use bind volumes to separate the OS from the tools installation and the workspace. In other words, the container has access to a few designated directories on the host from inside the container.

In this case, I designated three directories to use as bind volumes.

Tools volume: where Petalinux and Vivado SDK will be installed
Workspace volume: from where to run all projects
Installers volume: where to get the installer binaries

These volumes will be accessible from the container and from the host, and can be changed by using the docker run command.

Building

Docker is built from the Dockerfile, downloading the Linux distro and all dependencies and updates. The result is an image that is ready to work on installing the tools without issues.

$ sudo docker build . -t petalinux-centos

A couple of tweaks were needed to have VNC access and start the Xfce desktop on boot; copying created passwd and xstartup files to the container.

xstartup:

#!/bin/sh
unset SESSION_MANAGER
unset DBUS_SESSION_BUS_ADDRESS
exec /usr/bin/xfce4-session
exec /etc/X11/xinit/xinitrc

The passwd file can be created by using the vncpasswd command:

$ vncpasswd passwd

Running

The docker run command creates a fresh instance of the image, called a container. This container “boots” in under a second and it’s ready to go. A simple exit command stops the container.

$ sudo docker run --rm --entrypoint=/bin/bash \
      --user=plnx --name=petalinux-centos7 -ti \
      -v /home/user/Downloads:/home/plnx/resources:Z \
      -v /opt/docker-volumes/petalinux-2018.2-centos7.4:/opt:Z \
      -v /home/user/Workspace:/home/plnx/workspace:Z \
      petalinux-centos

I added a VNC server to have a GUI, necessary to run Vivado and SDK from the host (or any host on the network potentially). To start it:

[plnx@e94aab57a34e]$ vncserver -geometry 1500x1000 :1

Notice above, the prompt inside the container changes to the containers’ Id.

Installing tools

From the host we can open a VNC viewer such as Remmina or TigerVNC to see the container’s GUI at address 172.17.0.2:1

Inside the container we can run the Petalinux installer, as usual.

[plnx@e94aab57a34e]$ ./resources/petalinux-v2018.2-final-installer.run /opt/petalinux

Then, similarly with Vivado installer

[plnx@e94aab57a34e]$ ./resources/Xilinx_Vivado_SDK_Web_2018.2_0614_1954_Lin64.bin

All files will be installed in the Tools volume under /opt, but in reality the files reside (in this example) in the host at /opt/docker-volumes/petalinux-2018.2-centos7.4/

Conclusion

After the tools are installed, running a container is very fast and efficient and always starts at the same exact point based on the image. The volumes are persistent as they are located in the host’s drive, which can be helpful when switching tools versions or testing differences between builds. For my own usage, running a supported OS on my unsupported distro of choice was the main driver.

Dockerfile

FROM docker.io/centos:7.4.1708
MAINTAINER patocarr
LABEL Version 0.1

ENV container docker

# NOTE: Systemd needs /sys/fs/cgroup directoriy to be mounted from host in
# read-only mode. (Required).
# VOLUME [ "/sys/fs/cgroup" ]

# Systemd needs /run directory to be a mountpoint, otherwise it will try
# to mount tmpfs here (and will fail).  (Required).
VOLUME [ "/run" ]

RUN yum -y update                      && \
    yum -y install openssh xterm rsync && \
    yum clean all

RUN yum -y install xinetd gcc git zlib-devel ncurses-devel openssl-devel \
      libselinux1 bc unzip minicom screen net-tools gnupg diffstat \
      xorg-x11-server-Xvfb chrpath socat autoconf file \
      libtool bzip2 patch gcc-c++ texinfo automake glib2-devel \
      dos2unix iproute gawk gnutls-devel net-tools tftp-server flex bison \
      libstdc++.i686 glibc.i686 libgcc.i686 libgomp.i686 ncurses-libs.i686 \
      zlib.i686 fontconfig.i686 libXext.i686 libXrender.i686 glib2.i686 \
      libpng12.i686 libSM.i686 usbutils expect wget sudo which ; \
      yum clean all

RUN yum install -y epel-release tigervnc-server firefox
RUN yum --enablerepo=epel -y groups install Xfce
RUN yum clean all
RUN wget http://mirror.centos.org/centos/7/os/x86_64/Packages/libpng12-1.2.50-10.el7.x86_64.rpm
RUN rpm -ivh libpng12-1.2.50-10.el7.x86_64.rpm

RUN sed -ie 's/disable.*= yes/disable = no/' /etc/xinetd.d/tftp

RUN echo "%sudo ALL=(ALL:ALL) ALL" >> /etc/sudoers
RUN echo "%sudo ALL=(ALL) NOPASSWD:ALL" >> /etc/sudoers

# Set locale
#RUN localectl set-locale en_US.UTF-8
ENV LANG en_US.UTF-8  
ENV LANGUAGE en_US:en  
ENV LC_ALL en_US.UTF-8 

# Set up a user
RUN useradd --uid 1000 --groups wheel --system --create-home plnx
RUN echo "plnx:plnx" | chpasswd
WORKDIR /home/plnx

RUN chmod +w /opt && chown -R plnx:plnx /opt

USER plnx
RUN mkdir -p /home/plnx/workspace
RUN mkdir -p /home/plnx/.vnc

ADD xstartup /home/plnx/.vnc/xstartup
ADD passwd /home/plnx/.vnc/passwd

USER root
RUN chmod 600 /home/plnx/.vnc/passwd
RUN chown plnx /home/plnx/.vnc/passwd
RUN rm /tmp/.X1-lock || :

USER plnx
CMD /usr/bin/vncserver :1 -geometry 1280x800 -depth 24 && tail -f /home/plnx/.vnc/*:1.log


EXPOSE 22
EXPOSE 5901