Re: [PATCH v4 1/1] Documentation: real-time: Add kernel configuration guide

[Sebastian Andrzej Siewior]

On 2026-07-21 16:40:10 [+0206], John Ogness wrote:
> On 2026-07-21, Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> wrote:
> >> +``CONFIG_DEBUG_FS``
> >> +^^^^^^^^^^^^^^^^^^^
> >> +
> >> +This is safe to include in real-time kernels, *provided that debugfs is
> >> +not accessed during production runtime*.
> >
> > It is safe to have as long as you don't use it.
> >
> > I would drop it. That filesystem is not dangerous on its own. It depends
> > on the options you change and how this affect the system.
> > We used to have it always enabled because you needed it for tracing.
> > This is no longer the case as it has its own tracefs which has its own
> > live outside of debugfs. So I don't think it is needed to mention it.
> 
> Unfortunately, debugfs is needed to configure the fair deadline server:
> 
>     /sys/kernel/debug/sched/fair_server/cpu*/runtime

So drop the reference to it. It is not "bad" to have it enabled. It is
just an interface to other things. Same as sysfs except that debugfs has
no stable ABI unlike sysfs.

> John Ogness

Sebastian