automount-tracefs-debugfs

 1What:		/sys/kernel/debug/tracing
 2Date:		May 2008
 3KernelVersion:	2.6.27
 4Contact:	linux-trace-kernel@vger.kernel.org
 5Description:
 6
 7	The ftrace was first added to the kernel, its interface was placed
 8	into the debugfs file system under the "tracing" directory. Access
 9	to the files were in /sys/kernel/debug/tracing. As systems wanted
10	access to the tracing interface without having to enable debugfs, a
11	new interface was created called "tracefs". This was a stand alone
12	file system and was usually mounted in /sys/kernel/tracing.
13
14	To allow older tooling to continue to operate, when mounting
15	debugfs, the tracefs file system would automatically get mounted in
16	the "tracing" directory of debugfs. The tracefs interface was added
17	in January 2015 in the v4.1 kernel.
18
19	All tooling should now be using tracefs directly and the "tracing"
20	directory in debugfs should be removed by January 2030.