From owner-freebsd-hackers Thu Feb 13 12:58:17 1997 Return-Path: Received: (from root@localhost) by freefall.freebsd.org (8.8.5/8.8.5) id MAA07713 for hackers-outgoing; Thu, 13 Feb 1997 12:58:17 -0800 (PST) Received: from sendero.i-connect.net ([206.190.144.100]) by freefall.freebsd.org (8.8.5/8.8.5) with ESMTP id MAA07687 for ; Thu, 13 Feb 1997 12:58:09 -0800 (PST) Received: (from shimon@localhost) by sendero.i-connect.net (8.8.5/8.8.4) id NAA14808; Thu, 13 Feb 1997 13:55:50 -0800 (PST) Message-ID: X-Mailer: XFMail 1.1-alpha [p0] on FreeBSD Content-Type: text/plain; charset=iso-8859-8 Content-Transfer-Encoding: 8bit MIME-Version: 1.0 In-Reply-To: <199702121719.KAA00730@phaeton.artisoft.com> Date: Thu, 13 Feb 1997 13:40:41 -0800 (PST) Organization: iConnect Corp. From: Simon Shapiro To: Terry Lambert Subject: Re: Raw I/O Question Cc: freebsd-hackers@freebsd.org, julian@whistle.com, (Bruce Evans) Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk Hi Terry Lambert; On 12-Feb-97 you wrote: > > >it then calls the strategy routine for the device > > >which gets the kv region, > > >and extracts the phyical addresses again and > > >sets up the DMA > > >and then waits > > > > > >DMA is directly into the users pages.. > > > > Only for devices and device drivers that support and use DMA. > > And are not limited to 24 bit ISA I/O when the physical memory > target of the DMA is not above 16M. These will be bounced and > then copied to the users pages. Perfect. We will be using only the PCI version of the HBA's, and it does DMA on everything, command, status, data, etc. It supports Scatterr/Gather well in excess of what we understand FreeBSD to be able to utilize (up to 8192 segments per dma command, 32bit counters everywhere, bus mastering, etc. Not a problem. I cannot wait to see it work. Simon