Messages in this thread | | | Date | Tue, 26 May 2009 22:38:03 -0400 (EDT) | From | Steven Rostedt <> | Subject | Re: [RFC PATCH]debugfs:Fix terminology inconsistency of dir name to mount debugfs filesystem. |
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On Wed, 27 May 2009, GeunSik Lim wrote:
> On Wed, May 27, 2009 at 6:15 AM, Steven Rostedt <rostedt@goodmis.org> wrote: > > > > On Tue, 26 May 2009, Greg KH wrote: > >> > > >> > The filesystem Nazi's out there will argue that the proper place to mount > >> > the debugfs filesystem is /sys/kernel/debug. I personally find that > >> > location annoying. > >> > >> Why? > > > > Because it is too much to type ;-) > I think so. But, when we consider many developers that use linux kernel > source all over the world, I think that a regular rules or consistency > is important > as greg k-h explained. > > Recently, I read "ftrace-world.odp" presentation file of steven rostedt. > > For example, about Mounting debugfs... > #> mount -t debugfs nodev /sys/kernel/debug > OR > #> mkdir /debug > #> mount -t debugfs nodev /debug > > I want that we will reach a consensus about mount directory name of > debugfs filesystem to avoid confusing among the kernel developers. > > /debug/ ? > or /sys/kernel/debug/? > ..... > > Frankly speaking, I like /sys/kernel/debug/ rule is better than /debug/ rule > for consistency.
And this is why I always mention that directory.
> > > > >> > >> When I created debugfs, I was told that I had to pick a place to mount > >> it so that everyone could write scripts that "knew" where it would be. > >> > >> So we picked /sys/kernel/debug/ and the code creates the mount point to > >> put it there. Now distros actually mount debugfs at that location. > >> > >> So, now you don't like this? After it's become a standard? Ick. > >> > >> Becides, /debug/ is pretty presumptious, it's as if debugging the kernel > >> is a system-wide thing :) > >> > >> So please, don't use /debug/ use the standard, defined, and ACTUALLY > >> USED BY DISTROS TODAY mount point of /sys/kernel/debug/ > >> > >> If you want to create your own symlink from /debug/ to that location to > >> make it easier to type, feel free, but do not hard code any scripts to > >> use that location, or they are going to break. > > > > All my scripts search /proc/mounts to find where debugfs is mounted, then > > it uses that. > > > > Hmm, Not sure what packages in the distros use the default. I don't see > > the debugfs in /etc/fstab in any of my machines. > > > Yes.. In my case, I use linux distributions like Ubuntu 8.10, Fedora > 9/10, CENTOS 5.3 currently. This distributions use proc , tmpfs, > devpts, sysfs for official release > by default. >
The key thing is not to have scripts depend on a path. When debugfs is enabled in a kernel, you automatically get /sys/kernel/debug, so that is a natural place to mount it.
I have also suggested to people (as Greg suggested earlier to me) that you can mount it there and then make a soft link to it. Which also works.
I personally just mount it at /debug.
To handle the scripts problem, all my scripts start with:
# grep debugfs /proc/mounts | cut -d ' ' -f 2
I also have a C function to do a search for debugfs in /proc/mounts.
If you look in Documentation/trace/ftrace.txt I have:
=== To mount the debugfs system:
# mkdir /debug # mount -t debugfs nodev /debug
( Note: it is more common to mount at /sys/kernel/debug, but for simplicity this document will use /debug) ===
Thus it is a personal preference of mine to put it at /debug. But I do not hide the fact that it is recommended to be in /sys/kernel/debug. Heck, I'm the one that brought to light that path in this thread. I just curse it everytime I have to say it ;-)
-- Steve
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