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To: freebsd-hackers@freefall.cdrom.com
Subject: Ambidextrous Devices
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Date: Sat, 25 Feb 1995 14:18:55 +0000
From: Matt Thomas <matt@lkg.dec.com>
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I'm finishing a driver for the DEC DEFPA [PCI] and DEFEA [EISA] FDDI 
Controllers for FreeBSD.  

Though at the moment I'm stumped by a problem.  Except for the probe
and attach routines, the driver runs the exact code for either device.

Should I use two separate device names as in:

device          fea0 at isa? bio irq ? vector fea_intr
device          fpa0

or should I use one device name to refer to both?

device          pdq0 at isa? bio irq ? vector fea_intr
device          pdq1

If the latter, how do I get the PCI code to start at unit 1?  Can I set
the pdq_count variable to a non-zero value [Hmmm.  I should try that]?

If the former, how do I distinguish between fea unit 0 and fpa unit 0
in the same driver?  Do I really need separate init and reset routines
(which would common routines)?

Is config smart enough to understand that a source file could be
used by two difference devices?

Would separte device names be preferred by users or would a single one
be best?

Any ideas or feedback will be greatly appreciated,


Matt Thomas                          Internet:   matt@lkg.dec.com
U*X Networking                       WWW URL:    http://ftp.dec.com/%7Ethomas/
Digital Equipment Corporation        Disclaimer: This message reflects my
Littleton, MA                                    own warped views, etc.