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Date:      Mon, 1 Mar 1999 14:00:05 -0500 (EST)
From:      "Matthew N. Dodd" <winter@jurai.net>
To:        Poul-Henning Kamp <phk@critter.freebsd.dk>
Cc:        Nate Williams <nate@mt.sri.com>, Garrett Wollman <wollman@khavrinen.lcs.mit.edu>, Bill Paul <wpaul@skynet.ctr.columbia.edu>, current@FreeBSD.ORG
Subject:   Re: Request for review: changes to if_vlan.c 
Message-ID:  <Pine.BSF.4.02.9903011332370.15262-100000@sasami.jurai.net>
In-Reply-To: <18612.920311569@critter.freebsd.dk>

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On Mon, 1 Mar 1999, Poul-Henning Kamp wrote:
> In message <199903011751.KAA03774@mt.sri.com>, Nate Williams writes:
> >> > ! 		 * If the LINK1 flag is set, it means the underlying interface
> >> > ! 		 * can do VLAN tag insertion itself and doesn't require us to
> >> > ! 	 	 * create a special header for it. In this case, we just pass
> >> 
> >> Are we certain that all drivers are now doing if_media and no longer
> >> using IFF_LINK1 for that purpose?
> >
> >I believe the old isa devices do not use if_media, but I could be
> >wrong.  (if_ep comes to mind....)
> 
> And some new PCI devices doesn't either because if_media is hopelessly
> narrowtrack for real world devices :-(

As much as if_media sucks, it does have the ability to be extended in a
fariety of useful ways.  I'm fairly sure that once you get over the grotty
mess of code needed to use it in a given driver it will offer a much
better solution than the IFF_LINK[0-2] in terms of interface media
selection.  The fact that ifconfig can present a standard interface to the
user without them having to reference manual pages to determine the
semantics of the various link flags in the context of each different
driver is an obvious win.

From looking at the code I can't see how sys/net/if_vlan.c's use of LINK1
in any way impacts other code (in other drivers) that uses LINK1.  (I
can't see how its use of LINK1 as is accomplishes Bill's stated goals but
still.)

Might a new flag be used (I note that 0x0020 is unused) to indicate this
information?  What is the impact of increasing the width of if_flags from
a short to an int?

Files using IFF_LINK[0-2] and # of times present.

dev/pdq/pdq_ifsubr.c:1
dev/ppbus/if_plip.c:2
dev/vx/if_vx.c:5
i386/isa/if_ar.c:1
i386/isa/if_ep.c:3
i386/isa/if_sr.c:3
i386/isa/if_wl.c:1
i386/isa/if_zp.c:3
net/if.h:4
net/if_slvar.h:3
net/if_spppsubr.c:2
net/if_vlan.c:2
net/bridge.c:1
net/bridge.h:1
net/if_vlan.c.orig:1
pc98/pc98/lpt.c:2
pci/if_de.c:4
pci/if_tx.c:13
i4b/driver/i4b_ipr.c:2


-- 
| Matthew N. Dodd  | 78 280Z | 75 164E | 84 245DL | FreeBSD/NetBSD/Sprite/VMS |
| winter@jurai.net |      This Space For Rent     | ix86,sparc,m68k,pmax,vax  |
| http://www.jurai.net/~winter | Are you k-rad elite enough for my webpage?   |



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