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debugfs mount point

debugfs mount point

Posted Mar 14, 2009 1:22 UTC (Sat) by gregkh (subscriber, #8)
Parent article: A look at ftrace

Traditionally debugfs is supposed to be mounted at /sys/kernel/debug with the following command:

mount -t debugfs none /sys/kernel/debug/

That's the recommended place to put it.

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debugfs mount point

Posted Mar 16, 2009 19:33 UTC (Mon) by nevets (subscriber, #11875) [Link]

Although I do mention /sys/kernel/debug in ftrace.txt, I find that too much to type. But perhaps I should change my general instructions to be...

mount -t debugfs none /sys/kernel/debug/
ln -s /sys/kernel/debug /debug

debugfs mount point

Posted Mar 17, 2009 13:38 UTC (Tue) by tao (subscriber, #17563) [Link]

Hype? Not creating a spurious, mostly unused, directory in the root namespace seems a perfectly good reason...

debugfs mount point

Posted Mar 17, 2009 15:42 UTC (Tue) by vapier (subscriber, #15768) [Link]

i think you misread ... he said "type", not "hype"

debugfs mount point

Posted Mar 17, 2009 16:04 UTC (Tue) by nevets (subscriber, #11875) [Link]

Thanks, I was confused by what he meant by "Hype".

But to his question about spurious directories in root. I still have on many systems an empty /opt. How's that different? I think seeing a /debug directory is quite obvious to what it is. Are you that worried about an inode that is seldom used?

The only ones that ever complain about /debug are a few kernel developers that know that /sys/kernel/debug was made for that purpose. The majority of people that use ftrace seem to mount the debugfs on /debug.

Typing "cat /debug/tracing/trace" is much faster than typing
"cat /sys/kernel/debug/tracing/trace".

debugfs mount point

Posted Mar 19, 2009 3:01 UTC (Thu) by daniel (subscriber, #3181) [Link]

I prefer /debug over /sys/kernel/debug/. After all, this symbol only needs to be there for debugging, if present then it is unmistakable why it is there, and there is no real chance of collision.

debugfs mount point

Posted Mar 17, 2009 15:45 UTC (Tue) by vapier (subscriber, #15768) [Link]

personally, i prefer to avoid "nodev" when possible as overuse can result in `mount` output that isnt completely obvious at first ... yes, that info is also available later on, but us english readers scan from left to right and get bored fairly quickly :)

$ mount -t debugfs debugfs /sys/kernel/debug
$ mount | grep debugfs
debugfs on /sys/kernel/debug type debugfs (rw,noexec,nosuid,nodev)

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