Re: [RFC][PATCH] tracing: Deprecate auto-mounting tracefs in debugfs

Steven Rostedt <[email protected]> Tue, 17 Jun 2025 13:54:46 -0400
Newsgroups org.kernel.vger.linux-trace-users,org.kernel.vger.linux-fsdevel,org.kernel.vger.linux-kernel,org.kernel.vger.linux-perf-users,org.kernel.vger.linux-trace-kernel
Message-ID <[email protected]>

On June 17, 2025 1:41:07 PM EDT, Peter Zijlstra <peterz@infradead=2Eorg> w=
rote:
>On Tue, Jun 17, 2025 at 01:36:14PM -0400, Steven Rostedt wrote:
>> From: Steven Rostedt <rostedt@goodmis=2Eorg>
>>=20
>> In January 2015, tracefs was created to allow access to the tracing
>> infrastructure without needing to compile in debugfs=2E When tracefs is
>> configured, the directory /sys/kernel/tracing will exist and tooling is
>> expected to use that path to access the tracing infrastructure=2E
>>=20
>> To allow backward compatibility, when debugfs is mounted, it would
>> automount tracefs in its "tracing" directory so that tooling that had h=
ard
>> coded /sys/kernel/debug/tracing would still work=2E
>>=20
>> It has been over 10 years since the new interface was introduced, and a=
ll
>> tooling should now be using it=2E Start the process of deprecating the =
old
>> path so that it doesn't need to be maintained anymore=2E
>
>I've always used /debug/tracing/ (because /debug is the right place to
>mount debugfs)=2E You're saying this is going away and will break all my
>scripts?!

You could mount tracefs in /tracing too:

  # mount -t tracefs nodev /tracing=20

And update you scripts with a simple sed script=2E

-- Steve=20