Getting Started Guide for ACRN logical partition mode

The ACRN hypervisor supports a logical partition scenario in which the User OS (such as Clear Linux) running in a pre-launched VM can bypass the ACRN hypervisor and directly access isolated PCI devices. The following guidelines provide step-by-step instructions on how to set up the ACRN hypervisor logical partition scenario on Intel NUC while running two pre-launched VMs.

Validated Versions

  • Ubuntu version: 18.04
  • Clear Linux version: 32680
  • ACRN hypervisor tag: v1.6
  • ACRN kernel commit: 8c9a8695966d8c5c8c7ccb296b9c48671b14aa70


  • Intel Whiskey Lake
  • NVMe disk
  • SATA disk
  • Storage device with USB interface (such as USB Flash or SATA disk connected with a USB3.0 SATA converter).
  • Disable Intel Hyper Threading Technology in the BIOS to avoid interference from logical cores for the logical partition scenario.
  • In the logical partition scenario, two VMs (running Clear Linux) are started by the ACRN hypervisor. Each VM has its own root filesystem. Set up each VM by following the Install Clear Linux OS on bare metal with live server instructions and install Clear Linux OS (version: 32680) first on a SATA disk and then again on a storage device with a USB interface. The two pre-launched VMs will mount the root file systems via the SATA controller and the USB controller respectively.

Update kernel image and modules of pre-launched VM

  1. On your development workstation, clone the ACRN kernel source tree, and build the Linux kernel image that will be used to boot the pre-launched VMs:

    $ git clone
    Cloning into 'acrn-kernel'...
    $ cd acrn-kernel
    $ cp kernel_config_uos .config
    $ make olddefconfig
    scripts/kconfig/conf  --olddefconfig Kconfig
    # configuration written to .config
    $ make
    $ make modules_install INSTALL_MOD_PATH=out/

    The last two commands build the bootable kernel image as arch/x86/boot/bzImage, and loadable kernel modules under the ./out/ folder. Copy these files to a removable disk for installing on the NUC later.

  2. The current ACRN logical partition scenario implementation requires a multi-boot capable bootloader to boot both the ACRN hypervisor and the bootable kernel image built from the previous step. Install the Ubuntu OS on the on-board NVMe SSD by following the Ubuntu desktop installation instructions The Ubuntu installer creates 3 disk partitions on the on-board NVMe SSD. By default, the GRUB bootloader is installed on the EFI System Partition (ESP) that’s used to bootstrap the ACRN hypervisor.

  3. After installing the Ubuntu OS, power off the NUC. Attach the SATA disk and storage device with the USB interface to the NUC. Power on the NUC and make sure it boots the Ubuntu OS from the NVMe SSD. Plug in the removable disk with the kernel image into the NUC and then copy the loadable kernel modules built in Step 1 to the /lib/modules/ folder on both the mounted SATA disk and storage device with USB interface. For example, assuming the SATA disk and storage device with USB interface are assigned to /dev/sda and /dev/sdb respectively, the following commands set up the partition mode loadable kernel modules onto the root file systems to be loaded by the pre-launched VMs:

    # Mount the Clear Linux OS root filesystem on the SATA disk
    $ sudo mount /dev/sda3 /mnt
    $ sudo cp -r <kernel-modules-folder-built-in-step1>/lib/modules/* /mnt/lib/modules
    $ sudo umount /mnt
    # Mount the Clear Linux OS root filesystem on the USB flash disk
    $ sudo mount /dev/sdb3 /mnt
    $ sudo cp -r <path-to-kernel-module-folder-built-in-step1>/lib/modules/* /mnt/lib/modules
    $ sudo umount /mnt
  4. Copy the bootable kernel image to the /boot directory:

    $ sudo cp <path-to-kernel-image-built-in-step1>/bzImage /boot/

Update ACRN hypervisor image

  1. Before building the ACRN hypervisor, find the I/O address of the serial port and the PCI BDF addresses of the SATA controller nd the USB controllers on the NUC. Enter the following command to get the I/O addresses of the serial port. The NUC supports one serial port, ttyS0. Connect the serial port to the development workstation in order to access the ACRN serial console to switch between pre-launched VMs:

    $ dmesg | grep ttyS0
    [    0.000000] console [ttyS0] enabled
    [    1.562546] 00:01: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is
    a 16550A

    The following command prints detailed information about all PCI buses and devices in the system:

    $ sudo lspci -vv
    00:14.0 USB controller: Intel Corporation Sunrise Point-LP USB 3.0 xHCI Controller (rev 21) (prog-if 30 [XHCI])
            Subsystem: Intel Corporation Sunrise Point-LP USB 3.0 xHCI Controller
    00:17.0 SATA controller: Intel Corporation Sunrise Point-LP SATA Controller [AHCI mode] (rev 21) (prog-if 01 [AHCI 1.0])
            Subsystem: Intel Corporation Sunrise Point-LP SATA Controller [AHCI mode]
    00:1f.6 Ethernet controller: Intel Corporation Ethernet Connection I219-LM (rev 21)
            Subsystem: Intel Corporation Ethernet Connection I219-LM


    Verify the PCI devices BDF defined in the hypervisor/arch/x86/configs/whl-ipc-i5/pci_devices.h with the information reported by the lspci -vv command.

  2. Clone the ACRN source code and configure the build options.

    Refer to Build ACRN from Source to set up the ACRN build environment on your development workstation.

    Clone the ACRN source code and check out to the tag v1.6:

    $ git clone
    $ cd acrn-hypervisor
    $ git checkout v1.6

    Build the ACRN hypervisor with default xmls:

    $ make hypervisor BOARD_FILE=$PWD/misc/acrn-config/xmls/board-xmls/whl-ipc-i5.xml SCENARIO_FILE=$PWD/misc/acrn-config/xmls/config-xmls/whl-ipc-i5/logical_partition.xml RELEASE=0


    The acrn.32.out will be generated to ./build/hypervisor/acrn.32.out.

  3. Check the Ubuntu boot loader name.

    In the current design, the logical partition depends on the GRUB boot loader; otherwise, the hypervisor will fail to boot. Verify that the default boot loader is GRUB:

    $ sudo update-grub -V

    The above command output should contain the GRUB keyword.

  4. Check or update the BDF information of the PCI devices for each pre-launched VM; check it in the hypervisor/arch/x86/configs/whl-ipc-i5/pci_devices.h.

  5. Copy the artifact acrn.32.out to the /boot directory:

    1. Copy acrn.32.out to a removable disk.
    2. Plug the removable disk into the NUC’s USB port.
    3. Copy the acrn.32.out from the removable disk to /boot directory.

Update Ubuntu GRUB to boot hypervisor and load kernel image

  1. Append the following configuration to the /etc/grub.d/40_custom file:

    menuentry 'ACRN hypervisor Logical Partition Scenario' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-e23c76ae-b06d-4a6e-ad42-46b8eedfd7d3' {
            gfxmode $linux_gfx_mode
            insmod gzio
            insmod part_gpt
            insmod ext2
            echo 'Loading hypervisor logical partition scenario ...'
            multiboot --quirk-modules-after-kernel /boot/acrn.32.out
            module /boot/bzImage XXXXXX


    The kernel command line arguments used to boot the pre-launched VMs is located in the hypervisor/scenarios/logical_partition/vm_configurations.h header file and is configured by VMx_CONFIG_OS_BOOTARG_* MACROs (where x is the VM id number and * are arguments). The multiboot module param XXXXXX is the bzImage tag and must exactly match the kernel_mod_tag configured in the hypervisor/scenarios/logical_partition/vm_configurations.c file.

  2. Modify the /etc/default/grub file as follows to make the GRUB menu visible when booting:

    GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
  3. Update GRUB:

    $ sudo update-grub
  4. Reboot the NUC. Select the ACRN hypervisor Logical Partition Scenario entry to boot the logical partition of the ACRN hypervisor on the NUC’s display. The GRUB loader will boot the hypervisor, and the hypervisor will automatically start the two pre-launched VMs.

Logical partition scenario startup checking

  1. Use these steps to verify that the hypervisor is properly running:
    1. Log in to the ACRN hypervisor shell from the serial console.
    2. Use the vm_list to check the pre-launched VMs.
  2. Use these steps to verify that the two pre-launched VMs are running properly:
    1. Use the vm_console 0 to switch to VM0’s console.
    2. The VM0’s Clear Linux OS should boot up and log in.
    3. Use a Ctrl-Spacebar to return to the Acrn hypervisor shell.
    4. Use the vm_console 1 to switch to VM1’s console.
    5. The VM1’s Clear Linux OS should boot up and log in.

Refer to the ACRN hypervisor shell user guide for more information about available commands.