Sorry, what I meant was that FDs that aren’t sockets should be uniformly handled by the async IO syscalls rather than having to parse man pages or trip over EIN

Sorry, what I meant was that FDs that aren’t sockets should be uniformly handled by the async IO syscalls rather than having to parse man pages or trip over EINVALs to figure out the answers to questions like “can I select(2) on a pidfd? Can I O_NOBLOCK a regular on-disk file?”. For a concrete example, I should be able to select/poll/epoll any file descriptor. The multiplexers can short-circuit return for things where readiness is inherent (e.g. block device files/vfs, I’m not asking for the moon a la waiting for NFS shares to report ready or something). I should be able to issue non blocking reads on special file descriptors (timerfds, signalfds, eventfds, and so on). This is analogous to my other unachievable fantasy: everything that exposes a filesystem interface must work with inotify/kqueue/whatever. No exceptions for procfs/NFS/etc. At some point this fantasizing just becomes me griping about what made it to market/the worse-is-better philosophy generally, though. And yet it moves, I guess!