Subject: Re: marching unit numbers
To: Bill Sommerfeld <email@example.com>
From: Warner Losh <firstname.lastname@example.org>
Date: 12/31/1999 16:24:53
In message <199912311723.MAA01091@thunk.hamachi.org> Bill Sommerfeld writes:
: It looks like it shouldn't be difficult for those PCMCIA network
: interfaces which have te MAC address in the CIS (Card Info String)
: area on the card (which is accessible in a driver-independant way ..
: I'm told that many early PCMCIA cards don't support it, but the couple
: of newer ones I've looked at do have it). The pcmcia bus code could
: extract the MAC address and use it as a locator to match the
: appropriate device instance.
This is wrong. A substantial number of network cards do not have
their MAC Address in the CIS. The MAC Address extention is relatively
recent thing. I know that about 1/2 of the cards I have knocking
around for FreeBSD pccard work do not have this CIS tuple in them. I
see from the PAO work that a large number of cards do this in a
I think that this is going to be hard to do in general. You have a
chicken an egg problem. The driver will know how to get a unique
identifier from the device, if possible, but would have no place to
store that identifier that would be persistant accross a detach
(assuming that the softc goes away with the detach).