Re: [RFC PATCH] sysfs: Add /sys/kernel/realtime entry

On Fri, 10 Jul 2026 18:01:20 +0200
Florian Bezdeka <[email protected]> wrote:
> 
> Depends on what you consider a valid update scenario. Updating from 6.1-
> rt with sysfs available to something like 6.18 (no sysfs anymore) will
> still break - as long as you do not (force) update userspace in
> lockstep.

The key difference above is the drop of "-rt" in the version.

The "Don't break user space" rule is from Linus, and he only cares about
what is in his tree. It was never "some external tree supported this and
now that code from that tree is accepted in his tree, he must support this
other feature too". To get any feature in, it must be accepted by upstream
maintainers, regardless if without it, it breaks user space from the
out-of-tree code. Greg already showed his reluctance about this change.
It's people like Greg that get to decide if it gets upstream or not. In
their POV, it's *not* a regression.

> 
> I learned meanwhile that our detection moved to uname meanwhile, so this
> is not a problem for us anymore.

Then I guess it's not a problem :-)

-- Steve