On 2020-03-20, Eric Rannaud wrote: > Should we update the manpage to more fully explain the range of > possible errors or instead try to have more consistent errors? For > syscalls, what's the backward-compatibility contract for errno values? It's the same as everything else -- "if it breaks an existing application, it's a regression". There was an infamous case of this exact scenario happening (changing the errno returned from an ioctl broke pulseaudio) in 2012[1]. [1]: https://lore.kernel.org/lkml/CA+55aFzX56kPPwSO97X=UyPaMzV5QRNG9ScN=nxnHFjmz=_8yA@mail.gmail.com/ -- Aleksa Sarai Senior Software Engineer (Containers) SUSE Linux GmbH