.. SPDX-License-Identifier: GPL-2.0 ACRN Hypervisor Introduction ============================ The ACRN Hypervisor is a Type 1 hypervisor, running directly on bare-metal hardware. It has a privileged management VM, called Service VM, to manage User VMs and do I/O emulation. ACRN userspace is an application running in the Service VM that emulates devices for a User VM based on command line configurations. ACRN Hypervisor Service Module (HSM) is a kernel module in the Service VM which provides hypervisor services to the ACRN userspace. Below figure shows the architecture. :: Service VM User VM +----------------------------+ | +------------------+ | +--------------+ | | | | | |ACRN userspace| | | | | | +--------------+ | | | | |-----------------ioctl------| | | | ... |kernel space +----------+ | | | | | | HSM | | | | Drivers | | +----------+ | | | | +--------------------|-------+ | +------------------+ +---------------------hypercall----------------------------------------+ | ACRN Hypervisor | +----------------------------------------------------------------------+ | Hardware | +----------------------------------------------------------------------+ ACRN userspace allocates memory for the User VM, configures and initializes the devices used by the User VM, loads the virtual bootloader, initializes the virtual CPU state and handles I/O request accesses from the User VM. It uses ioctls to communicate with the HSM. HSM implements hypervisor services by interacting with the ACRN Hypervisor via hypercalls. HSM exports a char device interface (/dev/acrn_hsm) to userspace. The ACRN hypervisor is open for contribution from anyone. The source repo is available at https://github.com/projectacrn/acrn-hypervisor.