From owner-freebsd-hackers Tue Jun 3 09:06:01 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.5/8.8.5) id JAA06017 for hackers-outgoing; Tue, 3 Jun 1997 09:06:01 -0700 (PDT) Received: from labinfo.iet.unipi.it (labinfo.iet.unipi.it [131.114.9.5]) by hub.freebsd.org (8.8.5/8.8.5) with SMTP id JAA06009 for ; Tue, 3 Jun 1997 09:05:39 -0700 (PDT) Received: from localhost (luigi@localhost) by labinfo.iet.unipi.it (8.6.5/8.6.5) id RAA26497; Tue, 3 Jun 1997 17:25:54 +0200 From: Luigi Rizzo Message-Id: <199706031525.RAA26497@labinfo.iet.unipi.it> Subject: Re: DMA for IDE drives ? To: sos@sos.freebsd.dk (Søren Schmidt) Date: Tue, 3 Jun 1997 17:25:53 +0200 (MET DST) Cc: toor@dyson.iquest.net, hackers@FreeBSD.ORG In-Reply-To: <199706031539.RAA25432@sos.freebsd.dk> from "Søren Schmidt" at Jun 3, 97 05:39:26 pm X-Mailer: ELM [version 2.4 PL23] Content-Type: text Sender: owner-hackers@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk > In reply to Luigi Rizzo who wrote: > > Following the suggestion from John Dyson, I have downloaded the > > documents for the PIIX controller (i82371FB/i82371SB) which is used > > on several of our motherboards. > >=20 > > Maybe I am oversimplifying things but it seems that DMA for IDE > > could be implemented as follows: ... > Pretty to the point, but you also need code to check if the drive > really supports DMAr. the struct wdparam has to be enlarged. one bit per drive, there is one bit per drive reserved to this in the 82371 registers BMISTA (see the data sheets, page 77) :) It's a hack of course, since you also need to store somewhere the type of controller you are using. > I'm currently testing exactly this here, it seems to work so far. > More later... Great! Cheers Luigi -----------------------------+-------------------------------------- Luigi Rizzo | Dip. di Ingegneria dell'Informazione email: luigi@iet.unipi.it | Universita' di Pisa tel: +39-50-568533 | via Diotisalvi 2, 56126 PISA (Italy) fax: +39-50-568522 | http://www.iet.unipi.it/~luigi/ _____________________________|______________________________________