1. We build unikernels using the 'kraft container' which is Docker/OCI image[0][1] which has the necessary build tools to build Unikraft unikernels. We plug this into Concourse CI which builds thousands of combinations of Unikernels[2] as part of our code review process[3]. In addition to this, we have on-going research and tooling to help automatically discover permutations of Unikernel builds[4]. We then run the unikernel natively using the target platform/hardware combination or use QEMU emulation.

2. Really great question, but mostly you can expect the same functionality of an application when it runs as a unikernel because the application "thinks" it's still running in a traditional OS environment -- as it should be. Check out this documentation[5] (after step 7) about porting, it has snippets about where the boundary sometimes breaks. Even then, you can run it in POSIX-compatibility mode[6].

3. Well, general-purposes are not suited for deployment environments (which is what Unikraft is suited for). Installing Gentoo (or Ubuntu, Debian, for that matter) is a waste of resources if you only SSH in once to install your desired application.

[0]: https://unikraft.org/docs/usage/install/#docker

[1]: https://github.com/unikraft/kraft/tree/staging/package/docke...

[2]: https://builds.unikraft.io

[3]: https://unikraft.org/docs/contributing/review-process/#stage...

[4]: https://github.com/lancs-net/wayfinder

[5]: https://unikraft.org/docs/develop/porting/#providing-build-f...

[6]: https://unikraft.org/docs/features/posix-compatibility/