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

From: Dan Williams
Date: Fri Apr 18 2008 - 00:59:59 EST


On Thu, Apr 17, 2008 at 8:21 PM, Greg KH <greg@xxxxxxxxx> 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
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