Re: [linux-usb-devel] [RFC PATCH] debugfs - yet another in-kernel file system

[David Brownell <david-b@pacbell.net>]

On Thursday 09 December 2004 4:50 pm, Greg KH wrote:
> What if there was a in-kernel filesystem that was explicitly just for
> putting debugging stuff?  Some place other than proc and sysfs, and that
> was easier than both of them to use.  Yet it needed to also be able to
> handle complex stuff like seq file and raw file_ops if needed.

The problem with sysfs here is:  no seq_file support.
Otherwise it solves the basic "where to put the debug
files associated with "device X" or "driver Y" problems
in a good non-confusing way:  there are directories
already set up for devices and for drivers.

The problem with procfs here is that it doesn't have
such a naming solution:  there's no automatic mapping
betwen a /proc/driver/...file and its device, or vice
versa.  That issue is shared with debugfs.

Couldn't debugfs just be a thin shim on top of sysfs,
adding seq_file support?  Or on top of procfs, adding
device/driver naming domains, and maybe file-per-value
read/write support for drivers that want them?

What I'd really want out of a debug file API is to resolve
the naming issues, work with seq_file, and "softly and
silently vanish away".  I think this patch has the last
two, but not the first one!

- Dave