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Date: Wed, 4 Apr 2007 12:38:56 -0500
To: David Woodhouse <dwmw2@infradead.org>
Subject: Re: [PATCH] Stop pmac_zilog from abusing 8250's device numbers.
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From: linas@austin.ibm.com (Linas Vepstas)
Cc: linuxppc-dev@ozlabs.org, Paul Mackerras <paulus@samba.org>,
	linux-kernel@vger.kernel.org
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On Wed, Apr 04, 2007 at 12:34:53PM -0400, David Woodhouse wrote:
> On Wed, 2007-04-04 at 11:22 -0500, Linas Vepstas wrote:
> > The biggest problem would seem to be that the assignment would
> > depend on the detection order; there don't seem to be unique 
> > id's that would help udev consistently assign device names in 
> > consistent order. 
> 
> Of course there are. The different types of ports have different device
> numbers. As long as we don't do anything silly like putting all the
> serial drivers on the same major number, we can tell them apart
> relatively well.

Sure, but if two different pci serial cards are moved around  
to different pci slots, they'll be detected in a different order. 
Similarly if one has some usb-to-serial converter that might get
plugged in after boot, or maybe some serial port that shows up
only when a laptop is docked into a docking station.

--linas