smallkirby / zvm

ZVM: experimental toy VMM in Zig backed by KVM

ZVM: experimental toy VMM in Zig backed by KVM

ZVM is an experimental, educational, and just-for-fun minimal toy VMM. ZVM is entirely written in Zig language. ZVM is accelerated by KVM and Intel VT-x hardware virtualization extension. The implementation is minimal, but can boot Linux kernel v6.2.

Status

Under development... 🚧

Subject	Status
initram/initrd support	🌞
Boot init process	🌞
Configurable memory size	🌞
Keyboard interraction	🌞
Networking support (virtio-net)	🌧
Support multi cores	⛈
Switchable logging	⛅
Not depend on external libc	🌞
CI	⛅

Run

You need bzImage kernel image that is configured properly. The example config is available at /assets/config.linux. You also need initrd/initram image that contains your init process.

zig build run -- --kernel=<bzImage> --initrd=<initrd/initram>

It will automatically install dependency (ZVM uses ZON as a package manager), build ZVM, and run it. You can see all available options by zig build run -- --help:

$ zig build run -- --help
    -h, --help
            Display this help and exit.
    -k, --kernel <str>
            Kenel bzImage path.
    -i, --initrd <str>
            initramfs or initrd path.
    -m, --memory <str>
            Memory size. (eg. 100MB, 1G, 2000B)

You can change the log level by editing std_options variable in /src/main.zig. Available log levels are .debug, .info, .warn, and .err.

Tests

You possibly need root privilege to run tests depending on the capabilities you have.

zig build test --summary all

Supported Platforms

• Intel x64 with VT-x enabled
• Host OS: Any modern version of Linux
• Guest OS: Linux v6.2
• Zig v0.11.0
  • It might work on later versions until Zig introduces breaking changes. But it would happen soon, Zig is still not a mature language at all...

Notes

• DEVELOPMENT.md contains some notes that might help develop VMM.
• /hacks contains some pitfalls and hacks that I encountered during development.