Overview

A lightweight, bare-metal virtio backend library that enables developers to quickly implement virtio devices (e.g., virtio-net, virtio-blk) in hypervisors, VMMs, or other environments.

Features

• No OS dependencies — runs directly on physical hardware.
• Virtio 1.0 compliant - Support for split virtqueues.
• Support virtio-blk & virtio-net & virtio-console.
• Flexible I/O backend - Support for adding your own custom virtio device module.
• Isolate platform-specific code - The user implements a small set of callbacks for memory access, interrupt delivery...

Usage

Build

Build the standalone libraries with the default backend set:

make clean all

Use BUILD_DIR and OUTPUT_DIR to keep generated files outside the source tree:

make BUILD_DIR=/tmp/my-virtio-build OUTPUT_DIR=/tmp/my-virtio-output clean all

Backend modules are enabled by default and can be omitted with Make variables. For example, on a server that cannot build the bundled VNC backend:

make BACKEND_UI_VNC=n clean all

Available switches are BACKEND_BLK, BACKEND_NET, BACKEND_CONSOLE, BACKEND_GPU, BACKEND_INPUT, and BACKEND_UI_VNC. Enabled values are 1, y, yes, or true; any other value disables that module.

BACKEND_NET=n skips backend/virtio_backend_net.c and the bundled libslirp build. BACKEND_UI_VNC=n skips backend/virtio_backend_ui_vnc.c and the bundled libvncserver build. Disabled backend types cannot be created at runtime.

When this library is built through the QEMU subtree, pass the equivalent Meson options from a QEMU build directory:

mkdir -p build-myvirtio
cd build-myvirtio
../configure --target-list=riscv64-softmmu --enable-my-virtio --disable-docs \
  -Dmy_virtio_backend_ui_vnc=false
ninja qemu-system-riscv64

Multiple backend modules can be disabled together:

make BACKEND_NET=n BACKEND_UI_VNC=n clean all
mkdir -p build-myvirtio
cd build-myvirtio
../configure --target-list=riscv64-softmmu --enable-my-virtio --disable-docs \
  -Dmy_virtio_backend_net=false -Dmy_virtio_backend_ui_vnc=false
ninja qemu-system-riscv64

Source layout

virtio/      # Sources and internal headers for libMyVirtio.a
backend/     # Sources and internal headers for libMyVirtio_backend.a
template/    # Integration template showing how to wire both libraries

Output

After building, the following files are generated under the output/ directory:

output/
├── libMyVirtio.a      # Static library
├── libMyVirtio_backend.a
├── virtio_wrapper.h   # Public header for libMyVirtio.a
└── virtio_backend.h   # Public header for libMyVirtio_backend.a

Acknowledgements

Core virtqueue and device state machine logic derived from xvisor (see https://github.com/xvisor/xvisor.git). Thank you to the xvisor team for their pioneering open-source hypervisor work.

License

GPLv2 License -- see LICENSE.