Re: [PATCH 1/4] statx: Add a system call to make enhanced file info available

From: David Howells
Date: Tue Nov 22 2016 - 05:39:35 EST

Dave Chinner <david@xxxxxxxxxxxxx> wrote:

> No. Just provide a 64 bit high resoultion field, and define it to
> contain nanoseconds. When we need higher resolution to be exported
> to userspace, we use a /feature flag/ to indicate that is contains
> something like attoseconds or the like.

That sounds suspiciously like a bad idea - if you're talking about a flag with
a currently undefined meaning that the kernel can inflict on userspace without
warning to change the meaning of the nanoseconds field to something we haven't
defined yet.

Userspace would have to ask for it.