Date: Mon, 06 Sep 1999 12:49:17 -0700 From: Jason Thorpe <thorpej@nas.nasa.gov> To: Wes Peters <wes@softweyr.com> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: Tulip device driver question Message-ID: <199909061949.MAA02493@lestat.nas.nasa.gov>
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On Fri, 03 Sep 1999 16:23:00 -0600
Wes Peters <wes@softweyr.com> wrote:
> > > See, for instance, the al, ax, mx, pn, vr, and wb drivers. ;^)
> > ^^
> > Especially this one.. it's not a Tulip clone :-)
>
> Oh? vr(4) disagrees:
>
> The VIA Rhine chips use bus master DMA and have a software interface de-
> signed to resemble that of the DEC 21x4x "tulip" chips.
I don't care what the manual page says; take a look at the respective
programming manuals for the chips. Hell, take a look at if_vrreg.h and
if_pnreg.h. The vast differences are *very* obvious.
Really, the only thing that's even vaguely similar is that both of them
use chained descriptors which are 16 bytes long, with similar layout (but
not compatible bits within each longword).
The registers are totally different.
...tho, I guess he did say "resemble" ... The SiS 900 "resembles" a Tulip,
too (uses chained descriptors!), and the Tulip "resembles" the DEC SGEC
(a lot more than the Rhine "resembles" the Tulip, tho :-)
The various Tulip clones are actually somewhat close to Tulips (e.g. same
registers, for the most part, same bits in the registers), and can be driven
by the same driver, with various special cases in them for the (usually slight)
differences [this is the approach I'm taking in NetBSD; why Bill didn't write
a single driver for all the clones I'm not sure I'll ever know...]
> I found the above list by grepping for "-i tulip" in /usr/src/sys/pci. It
> is still a mystery to me why others don't do that before embarrassing them-
> selves on a public mailing list...
Hahaha.. Whatever :-)
-- Jason R. Thorpe <thorpej@nas.nasa.gov>
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