On Mon, Oct 07, 2002 at 11:26:35AM -0700, Randy.Dunlap wrote: > On Mon, 7 Oct 2002, Matthew Dharm wrote: > > | On Tue, Oct 08, 2002 at 01:11:01AM +1300, Michael Hamilton wrote: > | > 1. What part of the serial remains constant for the same device, > | > if any? > | > | The whole thing should. The compliance test that the USB-IF (including > | myself) are working on requires a constant serial number. > > Matt, do you read that as part of any spec (requirement)?
Not exactly. But the entire Mass Storage DWG was pretty supprised when I
pointed out devices that had this broken behavior.
The spec requires a 'unique' serial number, but does not specify what the
domain for that uniqueness is. The intent was to be unique over all
devices with that VID:PID. A few (a _very_ few) manufacturers chose to
interpret this as unique for a given USB bus.
The changing serial number is because the bus address is incorporated into
the serial number.
Of course, that means that it's possible to have two units on two different
USB busses with the same bus address, and thus the same serial number.
Matt
--
Matthew Dharm Home: [EMAIL PROTECTED]
Maintainer, Linux USB Mass Storage Driver
Your lips are twitching. You're playing Quake aren't you.
-- Stef to Greg
User Friendly, 8/11/1998
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