# crosvm
**The ChromeOS Virtual Machine Monitor**
[](LICENSE)
[](https://crosvm.dev/book/)
[](https://matrix.to/#/#crosvm:matrix.org)
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**crosvm** is a secure, lightweight, and performant Virtual Machine Monitor (VMM) written in Rust.
Originally developed for ChromeOS to run Linux ([Crostini](https://chromeos.dev/en/linux)) and
Android guests (ARCVM). It is now used across multiple products and platforms such as
[TerminalApp](https://cs.android.com/android/platform/superproject/main/+/main:packages/modules/Virtualization/android/TerminalApp/)
on Android, [Cuttlefish](https://github.com/google/android-cuttlefish) and Windows.
crosvm focuses on security through strong isolation and a modern, memory-safe implementation. It
leverages hardware-assisted virtualization to provide a robust execution environment for untrusted
code.
## 🌟 Core Philosophy
- **Security First**: Built with Rust's memory safety guarantees. Each virtual device can be run in
its own sandboxed process with restricted system access.
- **Isolation**: Uses Linux namespaces, seccomp filters, and Minijail to create a multi-layered
security boundary.
- **Performance**: Optimized for modern workloads with features like `io_uring`, `vhost`, and an
internal async runtime (`cros_async`).
- **Portability**: Supports multiple CPU architectures and hypervisor backends.
## 🛠️ Technical Specifications
### Supported Architectures
- **x86_64**
- **aarch64**
- **riscv64**
### Supported Hypervisors
- **Linux/Android**: KVM, Gunyah (Qualcomm), GenieZone (MediaTek), Halla (Exynos).
- **Windows**: WHPX (Windows Hypervisor Platform), HAXM (Intel).
### Virtio Device Support
crosvm implements a wide range of paravirtualized devices via the **virtio** standard:
- **Network**: `virtio-net` with optional vhost and slirp backends.
- **Storage**: `virtio-block` supporting raw, qcow2, zstd, and Android sparse formats.
- **Graphics**: `virtio-gpu` with 2D and 3D acceleration (via `virglrenderer`, `gfxstream`, or
`vulkano`).
- **Display/Input**: Integrated virtio gpu cross domain support for wayland passthrough
- **Audio**: `virtio-snd` with backends for CRAS (ChromeOS), AAudio (Android), and more.
- **File System**: `virtio-fs` and `virtio-9p`.
- **Other**: Console, RNG, Balloon, Vsock, TPM, Pmem, Video Decoder/Encoder, etc.
## 🔒 Security Architecture
crosvm is designed with a "process-per-device" model:
1. **Main Process**: Handles VM initialization and core orchestration.
1. **Device Processes**: Each virtio device can be `fork`ed into its own process.
1. **Sandboxing**: Each device process is jailed using
**[Minijail](https://github.com/google/minijail)**:
- **Namespaces**: VFS (pivot_root), PID, User, and Network isolation.
- **Seccomp**: Strict BPF filters restrict syscalls to only those required by the specific
device.
- **Capabilities**: All unnecessary Linux capabilities are dropped.
## 📖 Documentation
- **[User Guide & Documentation](https://crosvm.dev/book/)**: Comprehensive guide for users and
developers.
- **[Architecture Deep Dive](./ARCHITECTURE.md)**: Details on the internal design and communication
framework.
- **[API Documentation](https://crosvm.dev/doc/crosvm/)**: Auto-generated Rust API docs, useful for
searching internal types and functions.
- **[Source Code](https://chromium.googlesource.com/crosvm/crosvm/)**: The authoritative Chromium
Git repository.
- **[Contributor Guide](https://crosvm.dev/book/contributing/)**: Workflow and coding standards.
- Note that the GitHub repository is a read-only mirror. All contributions are submitted via
[Chromium Gerrit](https://chromium-review.googlesource.com/).
## 🚀 Getting Started
The recommended way to build and develop crosvm is using the provided development container.
### Prerequisites
- **Linux**: A modern kernel (5.x+) with KVM access.
- **Podman or Docker**: Installed and configured.
### Building
Use the dev container to build a release version of crosvm:
```bash
./tools/dev_container ./tools/build_release
```
### Basic Usage
Follow this [example usage](https://crosvm.dev/book/running_crosvm/example_usage.html) to run a
simple Linux guest.
## 🤝 Community & Support
- **[Announcements](https://groups.google.com/a/chromium.org/g/crosvm-announce)**: Join to watch for
announcements
- **[Matrix Chat](https://matrix.to/#/#crosvm:matrix.org)**: Join the `#crosvm` channel on Matrix.
- **[Issue Tracker](https://issuetracker.google.com/issues?q=status:open%20componentid:1161302)**:
Report bugs or request features.
- For Googlers: See [go/crosvm#filing-bugs](https://goto.google.com/crosvm#filing-bugs).
- **[Mailing List](https://groups.google.com/a/chromium.org/g/crosvm-dev)**: Developer discussions.
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crosvm is an open-source project licensed under the [BSD-3-Clause License](LICENSE).