Re: [Ksummit-discuss] [MAINTAINERS SUMMIT] Moving debugfs file systems into sysfs

[Jani Nikula <jani.nikula@intel.com>]

On Mon, 01 Oct 2018, Steven Rostedt <rostedt@goodmis.org> wrote:
> At Kernel Recipes, I talked with some people that have mature
> interfaces in the debugfs directory, but they can not access them on
> systems that have debugfs disabled. What would be the process to have
> these systems move out of debugfs? Should they create their own fs and
> be mounted in /sys/kernel, with a dedicated directory if the file system
> is enabled in the kernel (I had tracefs do that).
>
> Is this something we should discuss at Maintainers Summit? What is the
> process for mature debugfs directories? What's the justification to
> have them moved? Is there a better answer for this?

I have a semi-related topic, hopefully not a complete thread
hijack... ;)

I think module parameters should primarily be viewed as debug knobs
rather than ABI. Things should just work instead of requiring the user
to tweak module parameters. Of course, there's the whole spectrum
between ABI and "unsafe" module parameters, and parameters get added for
a plethora of reasons.

However, all module parameters show up in sysfs instead of, say,
debugfs. Many debug options otherwise suitable for debugfs alone are
added as module parameters because of the convenience; with just a few
lines you can add the module parameter, get the sysfs, and have the
value be set before probe. There's nothing that compares, really.

I suppose primarily I'd like to find a convenient way to move module
parameters to debugfs, so the other way round than Steven. Do others
struggle with this? Any ideas, thoughts, pointers?

BR,
Jani.

-- 
Jani Nikula, Intel Open Source Graphics Center