ubpf VS minivm

eBPF doesn't run in user space in the context of eBPF in the linux kernel. It's verified so that the kernel can be sure it won't loop forever and then gets JIT'ed and run in kernel space.

There are some user space BPF vms like https://github.com/iovisor/ubpf and Solana.

ubpf: https://github.com/iovisor/ubpf

The usual recommendation have been given. Now for more touristic approach what I would like to use if given excuse and time. All those options are mostly written in C:

- QBE [1] - small compiler backend with nice IL

- DynASM [2] - IIUC the laujit's backend, that can and is used by other languages

- uBPF - Userspace eBPF VM. Depending on your DSL the eBPF toolchain could fit your use-case, but this would probably be the biggest excursion.

[1] https://c9x.me/compile/

[2] https://luajit.org/dynasm.html

[3] https://github.com/iovisor/ubpf

There are eBPF-specific userspace implementations you can consider looking into but right now the best support for bpf would be the linux kernel so if the goal is learning you'll most likely want to run linux in a proper virtual machine (e.g. Qemu, VirtualBox, Parallels, etc.)

This may be entirely irrelevant to what you are looking for, but a good widely used finite register-based VM is the eBPF VM in the Linux Kernel. The IOVisor uBPF project (https://github.com/iovisor/ubpf) is a version of the VM in user space.

> I developed a unique way to write interpreters based on threaded code jumps and basic block versioning when I made MiniVM (https://github.com/FastVM/minivm). It was both larger and more dynamic than WebAssembly.

I'd be very interested to read more about this. It looks like you are using "one big function" with computed goto (https://github.com/FastVM/Web49/blob/main/src/interp/interp....). My experience working on this problem led me to the same conclusion as Mike Pall, which is that compilers do not do well with this pattern (particularly when it comes to register allocation): http://lua-users.org/lists/lua-l/2011-02/msg00742.html

I'm curious how you worked around the problem of poor register allocation in the compiler. I've come to the conclusion that tail calls are the best solution to this problem: https://blog.reverberate.org/2021/04/21/musttail-efficient-i...

Maybe take a look at MiniVM[0]? It was on HN a couple months ago[1].

[0]: https://github.com/fastvm/minivm

MiniVM: A zero-dependency cross-language runtime on par with LuaJIT and C\ (19 comments)