A crazy thought [LWN.net]

A crazy thought

Posted Jan 20, 2026 7:14 UTC (Tue) by edeloget (subscriber, #88392)
In reply to: A crazy thought by Cyberax
Parent article: Task-level io_uring restrictions

At this time, I feel that eBPF is mature enough to not being systematicly compared to WASM. It's also evolving faster. It's also more and more used outside the space of the Linux kernel (mostly in the network area).

If you really want a différent yet proven VM for the kernel, why WASM? Why not the Java VM? Or the Lua VM? Or any other VM that has been there for years?

Since the eBPF VM is already here, I think that anybody who wants another VM in the kernel will have to implement it, instead of requiring everyone to do it. Isn't that the idea behind Open Source ?

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A crazy thought

Posted Jan 20, 2026 7:32 UTC (Tue) by Cyberax (✭ supporter ✭, #52523) [Link] (4 responses)

Java VM is not well-suited for this, it needs classloading, object hierarchy, gc, and so on.

LUA would have been great, and it has been used successfully in BSDs in kernelspace.

> It's also evolving faster.

No, it's racing to become competitive with WASM circa 5 years ago. I'm now eagerly awaiting multithreading in eBPF.

A crazy thought

Posted Jan 20, 2026 17:23 UTC (Tue) by ballombe (subscriber, #9523) [Link] (3 responses)

> No, it's racing to become competitive with WASM circa 5 years ago. I'm now eagerly awaiting multithreading in eBPF.

WASM is still 32bit-only and progress on that have been slow.

A crazy thought

Posted Jan 20, 2026 18:50 UTC (Tue) by Cyberax (✭ supporter ✭, #52523) [Link] (2 responses)

Not anymore: https://webassembly.org/news/2025-09-17-wasm-3.0/

A crazy thought

Posted Jan 21, 2026 17:09 UTC (Wed) by ballombe (subscriber, #9523) [Link] (1 responses)

This is huge! Is there a version of emscripten that support LP64 available ?

A crazy thought

Posted Jan 24, 2026 20:35 UTC (Sat) by ballombe (subscriber, #9523) [Link]

In fact it works already, with emscripten 4.0.37 provided node is upgraded to 2.24 and -s MEMORY64 is added to CFLAGS. Congrats to everyone involved.