Certain limitations must be checked (e.g. can be proven to halt). It's a bit much for an HN post, see https://lwn.net/Articles/740157/ https://lwn.net/Articles

Certain limitations must be checked (e.g. can be proven to halt). It's a bit much for an HN post, see https://lwn.net/Articles/740157/ https://lwn.net/Articles/740157/ subsection "The eBPF in-kernel verifier" for more background.