Device Model Parameters

Hypervisor Device Model (DM) is a QEMU-like application in the Service OS (SOS) responsible for creating a UOS VM and then performing devices emulation based on command line configurations, as introduced in Device Model high-level design.

Here are descriptions for each of these acrn-dm command line parameters:

-A, --acpi Create ACPI tables. With this option, DM will build an ACPI table into its VMs F-Segment (0xf2400). This ACPI table includes full tables for RSDP, RSDT, XSDT, MADT, FADT, HPET, MCFG, FACS, and DSDT. All these items are programmed according to acrn-dm command line configuration and derived from their default value.
-B, --bootargs <bootargs>

Set the UOS kernel command line arguments. The maximum length is 1023. The bootargs string will be passed to the kernel as its cmdline.


-B "loglevel=7"

specifies the kernel log level at 7

-c, --ncpus <cpus> Set number of CPUs for UOS. This number is an integer and must not be more than the total number of CPUs in the system, minus one (which is used by the SOS).
--debugexit Enable guest to write io port 0xf4 to exit guest. It’s mainly used by guest unit test.
-E <elf image path> This option is to define a static elf binary which could be loaded by DM. DM will run elf as guest of ACRN.

Enable trusty for guest. For Android guest OS, ACRN provides a VM environment with two worlds: normal world and trusty world. The Android OS runs in the the normal world. The trusty OS and security sensitive applications runs in the trusty world. The trusty world can see the memory of normal world but not vice versa. See Trusty TEE for more information.

By default, the trusty world is disabled. Use this option to enable it.

-G, --gvtargs <GVT_args>

ACRN implements GVT-g for graphics virtualization (aka AcrnGT). This option allows you to set some of its parameters.

GVT_args format: gvt_high_gm_sz gvt_low_gm_sz gvt_fence_sz


  • gvt_high_gm_sz: GVT-g aperture size, unit is MB
  • gvt_low_gm_sz: GVT-g hidden gfx memory size, unit is MB
  • gvt_fence_sz: the number of fence registers


-G "10 128 6"

sets up 10Mb for GVT-g aperture, 128M for GVT-g hidden memory, and 6 fence registers.

-h, --help Show a summary of commands.
-i, --ioc_node <ioc_mediator_parameters>

IOC (IO Controller) is a bridge of an SoC to communicate with Vehicle Bus. It routes Vehicle Bus signals, for example extracted from CAN messages, from IOC to the SoC and back, as well as controlling the onboard peripherals from SoC. (The -i and -l parameters are only available on a platform with IOC.)

IOC DM opens /dev/ptmx device to create a peer PTY devices, IOC DM uses these to communicate with UART DM since UART DM needs a TTY capable device as its backend.

The device model configuration command syntax for IOC mediator is:

  • ioc_channel_path is an absolute path for communication between IOC mediator and UART DM.

  • lpc_port is com1 or com2. IOC mediator needs one unassigned lpc port for data transfer between User OS and Service OS.

  • wakeup_reason is IOC mediator boot up reason, where each bit represents one wakeup reason.

    Currently the wakeup reason bits supported by IOC firmware are:

    • CBC_WK_RSN_BTN (bit 5): ignition button.
    • CBC_WK_RSN_RTC (bit 9): RTC timer.
    • CBC_WK_RSN_DOR (bit 11): Car door.
    • CBC_WK_RSN_SOC (bit 23): SoC active/inactive.

As an example, the following commands are used to enable IOC feature, the initial wakeup reason is ignition button, and cbc_attach uses ttyS1 for TTY line discipline in UOS:

-i /run/acrn/ioc_$vm_name,0x20
-l com2,/run/acrn/ioc_$vm_name
--intr_monitor <intr_monitor_params>

Enable interrupt storm monitor for UOS. Use this option to prevent an interrupt storm from the UOS.

usage: --intr_monitor threshold/s probe-period(s) delay_time(ms) delay_duration(ms)


--intr_monitor 10000,10,1,100
  • 10000: interrupt rate larger than 10000/s will be treated as interrupt storm
  • 10: use the last 10s of interrupt data to detect an interrupt storm
  • 1: when interrupts are identified as a storm, the next interrupt will be delayed 1ms before being injected to the guest
  • 100: after 100ms, we will cancel the interrupt injection delay and restore to normal.
-k, --kernel <kernel_image_path>

Set the kernel (full path) for the UOS kernel. The maximum path length is 1023 characters. The DM handles bzImage image format.

usage: -k /path/to/your/kernel_image

-l, --lpc <lpc_device_configuration> (See -i, --ioc_node)
-m, --memsize <memory_size>

Setup total memory size for UOS.

memory_size format is: “<size>{K/k, B/b, M/m, G/g}”, and size is an integer.

usage: -m 4g: set UOS memory to 4 gigabytes.

--mac_seed <seed_string>

Set a platform unique string as a seed to generate the mac address. Each VM should have a different “seed_string”. The “seed_string” can be generated by the following method where $(vm_name) contains the name of the VM you are going to launch.

mac=$(cat /sys/class/net/e*/address)


-p, --pincpu <vcpu:hostcpu>

Pin host CPU to appointed vCPU:

  • vcpu is the ID of the CPU seen by the UOS, and
  • hostcpu is the physical CPU ID on the system.

Example: -p  "1:2" means pin the 2nd physical cpu to 1st vcpu in UOS

--part_info <part_info_name> Set guest partition info path.
--ptdev_no_reset Disable reset check for pci device. When assigning a PCI device as a passthrough device, we will reset it first to get it to a valid device state. So if the device doesn’t have the reset capability, the passthrough will fail. The PCI device reset can be disabled using this option.
-r, --ramdisk <ramdisk_image_path>

Set the ramdisk (full path) for the UOS. The maximum length is 1023. The supported ramdisk format depends on your UOS kernel configuration.

usage: -r /path/to/your/ramdisk_image

-s, --pci_slot <slot_config>

Setup PCI device configuration.

slot_config format is:



  • slot is 0..31
  • func is 0..7
  • emul is a string describing the type of PCI device e.g. virtio-net
  • config is an optional device-dependent string, used for configuration.


-s 7,xhci,1-2,2-2

This configuration means the virtual xHCI will appear in PCI slot 7 in UOS. Any physical USB device attached on 1-2 (bus 1, port 2) or 2-2 (bus 2, port 2) will be detected by UOS and be used as expected. To determine which bus and port a USB device is attached, you could run lsusb -t in SOS.

-s 9,virtio-blk,/root/test.img

This add virtual block in PCI slot 9 and use /root/test.img as the disk image

-U, --uuid <uuid>

Set UUID for a VM. Every VM is identified by a UUID. You can define that UUID with this option. If you don’t use this option, a default one (“d2795438-25d6-11e8-864e-cb7a18b34643”) will be used.


-u "42795636-1d31-6512-7432-087d33b34756"

set the newly created VM’s UUID to 42795636-1d31-6512-7432-087d33b34756

-v, --version Show Device Model version
--vsbl <vsbl_file_path>

Virtual Slim bootloader (vSBL) is the virtual bootloader supporting booting of the UOS on the ACRN hypervisor platform. The vSBL design is derived from Slim Bootloader, which follows a staged design approach that provides hardware initialization and launching a payload that provides the boot logic.

The vSBL image is installed on the Service OS root filesystem by the service-os bundle, in /usr/share/acrn/bios/. In the current design, the vSBL supports booting Android guest OS or Linux guest OS using the same vSBL image. For Android VM, the vSBL will load and verify trusty OS first, and trusty OS will then load and verify Android OS according to Android OS verification mechanism.


vSBL is currently only supported on Apollo Lake processors.


--vsbl /usr/share/acrn/bios/VSBL.bin

uses /usr/share/acrn/bios/VSBL.bin as the vSBL image

--ovmf [w,]<ovmf_file_path>

Open Virtual Machine Firmware (OVMF) is an EDK II based project to enable UEFI support for Virtual Machines.

ACRN does not support off-the-shelf OVMF builds targeted for QEMU and KVM. Compatible OVMF images are included in the source tree, under devicemodel/bios/.


--ovmf /usr/share/acrn/bios/OVMF.fd

uses /usr/share/acrn/bios/OVMF.fd as the OVMF image

ACRN supports option “w” of OVMF. To preserve any change of OVMF NV data store section, using this option to enable NV data store section writeback.


--ovmf w,/usr/share/acrn/bios/OVMF.fd
--virtio_poll <poll_interval>

Enable virtio poll mode with poll interval xxx ns.


--virtio_poll 1000000

enable virtio poll mode with poll interval 1ms.

--vtpm2 <sock_path> This option is to enable virtual TPM support. The sock_path is a mandatory parameter for this option which is the path of swtpm socket fd.
-W, --virtio_msix This option forces virtio to use single-vector MSI. By default, any virtio-based devices will use MSI-X as its interrupt method. If you want to use single-vector MSI interrupt, you can do so using this option.
-Y, --mptgen

Disable MPtable generation. The MultiProcessor Specification (MPS) for the x86 architecture is an open standard describing enhancements to both operating systems and firmware that allows them to work with x86-compatible processors in a multi-processor configuration. MPS covers Advanced Programmable Interrupt Controller (APIC) architectures.

By default, DM will create the MPtable for you. Use this option to disable it.


This option is to create a VM with the local APIC (LAPIC) passed-through. With this option, a VM is created with LAPIC_PASSTHROUGH and IO_COMPLETION_POLLING mode. This option is typically used for hard realtime scenarios.

By default, this option is not enabled.


This option is used to create a VM with realtime attributes. With this option, a VM is created with GUEST_FLAG_RT and GUEST_FLAG_IO_COMPLETION_POLLING mode. This kind of VM is generally used for soft realtime scenarios (without --lapic_pt) or hard realtime scenarios (with --lapic_pt). With GUEST_FLAG_RT, the Service OS (SOS) cannot interfere with this kind of VM when it is running. It can only be powered off from inside the VM itself.

By default, this option is not enabled.