Re: [PATCH mm] sysfs: add /sys/dev/usb to handle CONFIG_USB_DEVICE_CLASS=y

["Dan Williams" <dan.j.williams@intel.com>]

On Thu, Apr 17, 2008 at 8:21 PM, Greg KH <greg@kroah.com> wrote:
> On Thu, Apr 17, 2008 at 07:11:03PM -0700, Dan Williams wrote:
>
> > The deprecated config option CONFIG_USB_DEVICE_CLASS causes class devices
>  > with duplicate major:minor numbers to be registered.  In effect they
>  > represent a usb specific address space for major:minor numbers so add 'usb'
>  > as a directory along side 'block' and 'char'.
>
>  Hm, no they do not, they are not a new address space, we are just
>  reusing them as the other user wasn't using them, and the code is
>  deprecated and will be removed eventually.  Neither of these char
>  devices are really hooked up to anything within the kernel, so it
>  doesn't matter yet.
>
>  I wonder how many other duplicates we have floating around...
>

Hm, so how about making this an opt-in capability of the class?  At
device_add() time the class is queried to see if a link should be
created in /sys/dev/block or /sys/dev/char?  Although, this leads to
inconsistent coverage.  But maybe that does not matter as many of
these character devices do not have interesting attributes to be
accessed?  Sigh, I am beginning to wonder if the character device side
of this capability is a solution looking for a problem...

Ideas?

>  thanks,
>
>  greg k-h
>

Thanks,
Dan