Build a User VM from the Clear Linux OS

This document builds on Getting Started, and explains how to build a User VM from Clear Linux OS.

Build User VM image from Clear Linux OS

Follow these steps to build a User VM image from the Clear Linux OS:

  1. In Clear Linux OS, install ister (a template-based installer for Linux) included in the Clear Linux OS bundle os-installer. For more information about ister, please visit

    $ sudo swupd bundle-add os-installer
  2. After installation is complete, use to generate the image for a User VM with the configuration in uos-image.json:

    $ cd ~
    $ sudo -t uos-image.json

    An example of the configuration file uos-image.json:

        "DestinationType" : "virtual",
        "PartitionLayout" : [ { "disk" : "uos.img",
                                "partition" : 1,
                                "size" : "512M",
                                "type" : "EFI" },
                              { "disk" : "uos.img",
                                "partition" : 2,
                                "size" : "1G",
                                "type" : "swap" },
                              { "disk" : "uos.img",
                                "partition" : 3,
                                "size" : "8G",
                                "type" : "linux" } ],
        "FilesystemTypes" : [ { "disk" : "uos.img",
                                "partition" : 1,
                                "type" : "vfat" },
                              { "disk" : "uos.img",
                                "partition" : 2,
                                "type" : "swap" },
                              { "disk" : "uos.img",
                                "partition" : 3,
                                "type" : "ext4" } ],
        "PartitionMountPoints" : [ { "disk" : "uos.img",
                                     "partition" : 1,
                                     "mount" : "/boot" },
                                   { "disk" : "uos.img",
                                     "partition" : 3,
                                     "mount" : "/" } ],
        "Version": "latest",
        "Bundles": ["bootloader",


    To generate the image with a specified version, please modify the "Version" argument, and we can set "Version": 26550 instead of "Version": "latest" for example.

    Here we will use "Version": 26550 for example, and the User VM image called uos.img will be generated after successful installation. An example output log is:

    Reading configuration
    Validating configuration
    Creating virtual disk
    Creating partitions
    Mapping loop device
    Creating file systems
    Setting up mount points
    Starting swupd. May take several minutes
    Installing 9 bundles (and dependencies)...
    Verifying version 26550
    Downloading packs...
    Extracting emacs pack for version 26550
    Extracting vim pack for version 26550
    Cleaning up
    Successful installation
  3. On your target device, boot the system and select “The ACRN Service OS”, as shown below:

    => The ACRN Service OS
    Clear Linux OS for Intel Architecture (Clear-linux-iot-lts2018-4.19.0-19)
    Clear Linux OS for Intel Architecture (Clear-linux-iot-lts2018-sos-4.19.0-19)
    Clear Linux OS for Intel Architecture (Clear-linux-native.4.19.1-654)
    EFI Default Loader
    Reboot Into Firmware Interface

Start the User VM

  1. Mount the User VM image and check the User VM kernel:

    # losetup -r -f -P --show ~/uos.img
    # mount /dev/loop0p3 /mnt
    # ls -l /mnt/usr/lib/kernel/
    default-iot-lts2018 -> org.clearlinux.iot-lts2018.4.19.0-26
  2. Adjust the /usr/share/acrn/samples/nuc/ script to match your installation. These are the couple of lines you need to modify:

    -s 3,virtio-blk,~/uos.img \
    -k /mnt/usr/lib/kernel/default-iot-lts2018  \


    User VM image uos.img is in the directory ~/ and User VM kernel default-iot-lts2018 is in /mnt/usr/lib/kernel/.

  3. You are now all set to start the User OS (User VM):

    $ sudo /usr/share/acrn/samples/nuc/

    You are now watching the User OS booting up!