Hacker News Reader

Comment by 7373737373 | Hacker News Reader

It's only a matter of time until we have metered WebAssembly in the kernel :)

Actually, why not? The main reason that "in the kernel" is concerning is because untrusted code needs some kind of sandboxing, either by static analysis or by run-time checks. (Most modern systems do a combination of both).

After all, the whole "in the kernel" vs. "in userland" distinction only exists because we get hardware-accelerated sandboxing from the CPU and OS combined.

Yeah, my comment is actually unironic :)

There are a few ways to limit the execution time of wasm programs:

- inject code after a set of instructions with a certain duration and in each loop that calls an external function which meters and destroys/suspends execution when a limit is reached (e.g. https://github.com/ewasm/wasm-metering)

- use a VM which counts instructions (e.g. https://github.com/perlin-network/life)

- use hardware interrupts

More random thoughts: https://esolangs.org/wiki/RarVM

I guess running an alternative language in kernel is not very challenging. (I tried it two years ago and managed to run i8042 keyboard driver in WebAssembly on Qemu) The hard part is interoperability. Even in languages with automatic C header -> native prototypes conversion capabilities, many kernel features are still not properly handled, especially the macros. Status quo requires the user to manually extract wrappers which could be super tedious.

Reply on news.ycombinator.com