Re: [RFC] subclasses in sysfs to solve world peace

[Kay Sievers <kay.sievers@vrfy.org>]

On Thu, Sep 15, 2005 at 07:58:44PM -0500, Dmitry Torokhov wrote:
> On Thursday 15 September 2005 19:20, Greg KH wrote:
> > I would like to add something called "subclasses" for lack of a better
> > term.  These subclasses would have both drivers, and devices associated
> > with them.  This would show up as the following tree of directories:
> > 
> > 	/sys/class/input/
> > 	|-- input0
> > 	|   |-- event0
> > 	|   `-- mouse0
> > 	|-- input1
> > 	|   |-- event1
> > 	|   `-- ts0
> > 	|-- mice
> > 	`-- drivers
> > 	    |-- event
> > 	    |-- mouse
> > 	    `-- ts
> > 
> > Here we have 3 struct class_devices like today, input0, input1, and
> > mice.  We also have struct subclass_drivers of event, mouse, and ts.
> > These will create the struct subclass_devices event0, mouse0, event1,
> > and ts0.  The "dev" node files will show up in the directories mice,
> > event0, mouse0, event1, and ts0, like you would expect them too.
> 
> This proposed scheme does not answer the question: "what input interfaces
> present in my system?".

If this is really needed, we can just create a "interfaces" directory at
every "class" top-level and put symlinks pointing to all interfaces of that
class into it. How does that sound?

> Input interfaces are objects in their own right
> and deserve their own spot. Compare your picture with the one below:
> 
> [dtor@core ~]$ tree /sys/class/input/
> /sys/class/input/
> |-- devices
> |   |-- input0
> |   |   |-- device -> ../../../../devices/platform/i8042/serio1
> |   |   `-- event0 -> ../../../../class/input/interfaces/event0

> `-- interfaces
>     |-- event0
>     |   |-- dev
>     |   `-- device -> ../../../../class/input/devices/input0
> 
> Here you have exactly the same information as in your picture plus you can
> see the other class (input interfaces) as well.

Well, this is just putting two different classes into one subdirectory. :)
We would better just add "/sys/class/input_device" and don't need to change
any userspace software then.
Sure there is the cosmetical difference that the two classes are just named
input* and not live in the same directory, but that's not enough reason
to start a complete different model in sysfs, I think.

I would like to have the option to move "block" into "class" some day
and therefore prefer the "stacking class devices", compared to the "grouping
and symlinking" classes model.

Kay