ACRNDormant

ACRN (pronounced “acorn”) runs on bare metal using Intel VT and is about 40,000 lines of code; its documentation compares that with more than 150,000 for data-centre hypervisors. It is built to consolidate workloads that used to need separate devices, such as soft PLCs, robotics control and general-purpose desktops, onto one Intel-based industrial or automotive computer. Pre-launched VMs are started by the hypervisor itself at boot with their own CPU cores, memory and devices, and run independently of everything else: a real-time VM (RTVM) running Zephyr, VxWorks or Xenomai for latency-critical control, or a Safety VM that watches for hardware failures and takes emergency action. A Service VM, normally Ubuntu, owns most of the remaining hardware and runs the Device Model, a user-space program that emulates devices and launches post-launched User VMs (Ubuntu, Windows, Android through Intel’s Celadon) that share that hardware through it.

Three scenarios combine these. A shared scenario has a Service VM and post-launched VMs; a partitioned scenario has only pre-launched VMs, with no Service VM or Device Model; a hybrid scenario mixes the two. The layout is fixed before build time: the Board Inspector records the target hardware in a board XML file, the ACRN Configurator turns that into a scenario XML file of VMs, CPU affinity and devices, and the hypervisor is compiled for that scenario and installed as Debian packages. ACRN was announced as a Linux Foundation project in March 2018 with ADLINK, Aptiv, Intel, LG Electronics and Neusoft as early members, and TTTech and ADLINK shipped products on it. Activity has since faded: v3.3 in August 2024, which requires Ubuntu 22.04 on the target, is the latest release, the main branch had 26 commits in 2025 and none so far in 2026, and the project website’s newest dated news is from 2021.