Subject: Re: USB feedback wanted
To: Bill Sommerfeld <>
From: Jonathan Stone <jonathan@DSG.Stanford.EDU>
List: tech-kern
Date: 06/30/1998 13:20:08
>What if I have multiple ostensibly "identical" (but not
>interchangeable) devices plugged into the bus...  How do I nail down
>the configuration so that the mapping from device-driver minor numbers
>to physical devices remains the same?  even if I temporarily
>plug/unplug yet another device?

>Think of a monophonic speaker.  Assume I have two plugged in as my
>`left' and `right' stereo channels.  if I just let the mapping
>"float", what happens if I add a third speaker, and it happens to come
>"before" the other two in the autoconfig order?  does the new one
>become "left", the old "left" become "right" and the old "right" get
>nothing at all?

If you think that's bad, wait till you try it with USB Ethernet

Trying to make the kernel automagically "get it right" , using only
bus-specific locators, when you can pull out, change, and reorder
devices "on the fly", seems like a lose to me.

The same problem comes up with PCMCIA, too...