MonoVM Embedding sample

WARNING This code is EXPERIMENTAL and not supported.

A sample suite of projects to show how to embed the .NET 6 MonoVM in a native desktop application.

Limitations

Only works on OSX or Debian 11, or Ubuntu 20.04 (other recent Linux distros may work too)
This is a limitation of the sample, not a limitation of the MonoVM itself. Embedding on other platforms where Mono works (Windows, Android, iOS) is possible. PRs welcome!
It needs the mono embedding hearders which are currently not included in the runtime packs (dotnet/runtime#46461), the sample includes them in the vendor/mono-headers/ directory, but this is not a good idea.
Until dotnet/runtime#49661 is fixed, Linux builds need patchelf

Help Wanted

If there's a problem in the sample open an Issue in this repo
If the sample doesn't work open an Issue in dotnet/runtime and mention "Mono embedding API"
If you can improve the sample please open a PR

Prerequisites

.NET 6 SDK
A C compiler
GNU Make
(Linux only) patchelf (Ubuntu has a .deb package)

Building

Just run make from the toplevel folder

Running

Run make run, or out/native/main directly. (You may need to set LD_LIBRARY_PATH on Linux)

Expected output:

runtime initialized
.NET 6.0.1
Hello From Managed

Detailed description of the sample

See DETAILS.md

Using a local build of the runtime

This is the process for using this sample with a local build of the runtime.

Building the runtime

Build a checkout of dotnet/runtime using something like

./build.sh -s mono+libs -c Release

Verify that artifacts/bin/microsoft.netcore.app.runtime.osx-x64/Release (or other RID and configuration) exists. It should contain a runtimes/osx-x64/native directory. The makefile dependson it.

Local build limitations

The CsharpSample is compiled using a normal (installed) dotnet SDK, so it won't be able to directly use any new managed APIs from the dotnet/runtime checkout. If the new API is in System.Private.CoreLib.dll, you may be able to call it using reflection.
We will take most libraries from the normal installed dotnet runtime, the only thing we pick up from the local build is libcoreclr.dylib and System.Private.CoreLib.dll this may lead to broken apps.
If you add a new MONO_API and want ot use it in the native sample, you will need to update the headers in vendor/mono-headers to include it.

Building the sample

Pass the LOCAL_RUNTIME variable on the make command line:

make LOCAL_RUNTIME=~/work/runtime/artifacts/bin/microsoft.netcore.app.runtime.osx-x64/Release
make LOCAL_RUNTIME=~/work/runtime/artifacts/bin/microsoft.netcore.app.runtime.osx-x64/Release run

The output from running should be

runtime initialized
.NET 7.0.0-dev
Hello From Managed

If it doesn't say .NET 7.0.0-dev it's not using the local build.

When in doubt, rm -rf out/ and try again.

lambdageek/monovm-embed-sample