Saint's Log

Ubuntu VM Setup for OpenJDK Development

I’m using a Windows 10 physical machine for my OpenJDK 17 development. Unfortunately, I ran into some issues getting the environment set up to build the JDK on Windows. To work around this, I created a Linux virtual machine. Although the instructions for building on Linux are on the OpenJDK site, I would like to have all the instructions in one spot, hence this post.

Creating an Ubuntu VM in Hyper-V

1. Download an LTS Ubuntu .iso from the Ubuntu Desktop download page. I selected Ubuntu 20.04.3 LTS.
2. Go to New > Virtual Machine in Hyper-V manager.
   1. Enter your VM name, generation, memory amount and type
   2. Select the connection type (Default Switch) and create a new virtual hard disk
   3. Select “Install an operating system from a bootable CD/DVD-ROM” then enter the path to the downloaded .iso file then click on Finish.
   4. Before starting the VM, set the number of virtual processors (it defaults to 1, which is less than ideal)!
3. Perform a normal Ubuntu installation including erasing the disk

Let us now review the more interesting steps – those related to configuring the Ubuntu environment.

Increase the Resolution of the Ubuntu Guest OS

The default 1024×768 screen resolution of the Ubuntu guest is rather restrictive. The solution to this comes from https://askubuntu.com/questions/384602/ubuntu-hyper-v-guest-display-resolution. We need to configure the Hyper-V Synthetic Video Frame Buffer Driver by adding ” video=hyperv_fb:1680×1050” to the GRUB_CMDLINE_LINUX_DEFAULT value in the /etc/default/grub file.

sudo apt-get install linux-image-extra-virtual
sudo apt-get install vim
sudo vim /etc/default/grub
sudo update-grub
reboot

Install the development dependencies

The table below lists the JDK build dependencies and the commands to install them.

This single command suffices to install all these components.

sudo apt-get install autoconf git build-essential libx11-dev libxext-dev libxrender-dev libxrandr-dev libxtst-dev libxt-dev libcups2-dev libfontconfig1-dev libasound2-dev

Install a code editor

Download the Visual Studio Code .deb file from https://code.visualstudio.com/Download. We can then install VS Code by running:

sudo apt install ~/Downloads/code_1.62.3-1637137107

Install a Boot JDK

I use the Microsoft OpenJDK build as the boot JDK. Here are the Ubuntu instructions for Installing the Microsoft Build of OpenJDK:

# Valid values are only '18.04' and '20.04'
# For other versions of Ubuntu, please use the tar.gz package
ubuntu_release=`lsb_release -rs`
cd ~/Downloads/
wget https://packages.microsoft.com/config/ubuntu/${ubuntu_release}/packages-microsoft-prod.deb -O packages-microsoft-prod.deb
sudo dpkg -i packages-microsoft-prod.deb
sudo apt-get install apt-transport-https

sudo apt-get update
sudo apt-get install msopenjdk-17

Verify that everything is working by running “java -version”

Clone and Build the JDK

Clone the JDK. Note that cloning a fork might be much slower than cloning the upstream Github repo! I was averaging about 60KiB/s on my rork whereas cloning the upstream OpenJDK was averaging 6 MiB/s when receiving objects!

mkdir ~/repos
cd ~/repos
git clone https://github.com/openjdk/jdk

The JDK repo can now be configured and built

cd jdk
bash configure
make images

The configure command should display any missing dependencies that it needs and a suggestion for how to install them.

To try out your new build, switch to the bin folder and check the Java version:

cd ~/repos/jdk/build/linux-x86_64-server-release/jdk/bin
./java -version

To browse through the contents of the build folder in a file manager:

xdg-open ./build