Re: [linux-usb] Re: USB device allocation

Brian Swetland (swetland@be.com)
Tue, 5 Oct 1999 17:34:05 -0700

["Michael S. Fischer" <otterley@dynamine.net>]
> Johannes Erdfelt <jerdfelt@sventech.com> wrote:
>
> > Microsoft doesn't use device nodes, but they solve the naming issue with
> > GUID, Globally Unique Identifiers. This is something that has been
> > brought up before.
>
> Was a decision re: GUIDs make WRT Linux? Seems (at least on the surface) to
> be an interesting idea. The major obstacle I see here is ensuring a GUID is
> truly globally unique. Given the fact that many USB peripherals don't
> follow the spec to the letter and therefore don't include serial numbers in
> their identifiers, this may not be possible. I wonder how Windows deals
> with this.

Unless I'm much mistaken, serial numbers are optional but encouraged (though
perhaps some class specs are more strict). I recall seeing something along
the lines of "if serial numbers are used they should be unique".

> > Also, Windows doesn't differentiate between different Mice for instance,
> > they all move the one cursor on the screen.
>
> FWIW, this is standard Macintosh behaviour (at least on the ADB it was; I
> don't know how USB-based mice on the Mac behave) as well.

BeOS works the same way -- the input_server listens to any mouse/keyboard/etc
device it can find and all events go through the same path.

Brian

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