[umanwizard]

> Fighting the ebpf validator is a bit like fighting Rust's borrow checker

I think this undersells how annoying it is. There's a bit of an impedance mismatch. Typically you write code in C and compile it with clang to eBPF bytecode, which is then checked by the kernel's eBPF verifier. But in some cases clang is smart enough to optimize away bounds checks, but the eBPF verifier isn't smart enough to realize the bound checks aren't needed. This requires manual hacking to trick clang into not optimizing things in a way that will confuse the verifier, and sometimes you just can't get the C code to work and need to write things in eBPF bytecode by hand using inline assembly. All of these problems are massively compounded if you need to support several different kernel versions. At least with the Rust borrow checker there is a clearly defined set of rules you can follow.