Subject: Re: Changes to link layer input routines
To: None <thorpej@nas.nasa.gov>
From: Anders Magnusson <ragge@ludd.luth.se>
List: tech-net
Date: 05/15/1999 20:24:56
> On Sat, 15 May 1999 19:46:49 +0200 (MET DST) 
>  Anders Magnusson <ragge@ludd.luth.se> wrote:
> 
>  > > 
>  > > 	(3) The VAX Unibus and Q-bus Ethernet drivers confused the h*ll
>  > > 	    out of me, and I didn't even try to clean up the way they
>  > > 	    use separate Unibus mapping registers for the Ethernet header
>  > > 	    and the actual packet.  (Wacky, it's not like they even support
>  > > 	    trailers in the driver!)
>  > > 
>  > Don't care so much about that; I'm going to change a lot of the uba
>  > mapping code. Welcome, bus_dma :-)
> 
> Excellent!  Are you going to model it after the Alpha SGMAP code?  :-)
> 
Yes, most of which is applicable. I have a Qbus MIPS machine waiting at 
home in Sweden when I return, therefore I need to do this :-)

>  > About trailers: A fast check shows that someone was cleaning up the 
>  > code maybe a little bit too much a while ago (Hey, Charles :-)
>  > 
>  > cvs log if_uba.c
>  > ...
>  > revision 1.5
>  > date: 1995/04/11 06:16:38;  author: mycroft;  state: Exp;  lines: +3 -15
>  > Sync with the rest of the world.  Say goodbye to Mr. Trailer.
>  > ----------------------------
>  > ...
> 
> Ah!  Okay, this is nice.  I think we should change ether_ifattach() to
> simply set IFF_NOTRAILERS everywhere, then.  I mean, it's not like anyone
> USES trailers anymore :-)  And, really, no other Ethernet interfaces
> would support them (that I know of).
> 
Or remove the IFF_NOTRAILERS flag totally, it's use is deprecated anyway.
The only thing is that trailer packets must be received, which doesn't
work quite well right now. That should actually be a compile-time option or
something like TCP_COMPAT_42.

-- Ragge