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.