Date: Fri, 10 Oct 1997 18:06:28 +0930 From: Mike Smith <mike@smith.net.au> To: Kenneth Merry <ken@plutotech.com> Cc: mike@smith.net.au (Mike Smith), tlambert@primenet.com, sos@sos.freebsd.dk, lederer@bonn-online.com, hackers@FreeBSD.ORG, gibbs@plutotech.com Subject: Re: HP 7100i Message-ID: <199710100836.SAA01577@word.smith.net.au> In-Reply-To: Your message of "Thu, 09 Oct 1997 22:18:14 CST." <199710100418.WAA23725@pluto.plutotech.com>
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> Mike Smith wrote... > > I was just about to mail Justin and ask if there was any documentation > > on writing code to layer under his new CAM stuff. I have a copy of the > > T13 1153Dr16 document here, and have been studying it in a little > > detail. > > > > So, is there? > > Well, nothing specifically about the FreeBSD implementation. But, > there are the CAM and CAM-3 specs: > > http://www.symbios.com/x3t10/io/t10/drafts/cam/cam-r12b.pdf > http://www.symbios.com/x3t10/io/t10/drafts/cam3/cam3r02.pdf Snarfen... > > I think the way to go, if you want to add IDE support to the > FreeBSD CAM code, is to write another transport layer to go alongside the > current transport layer. Justin can elaborate on it a little more. (I've > CCed him..) The situation is a little complicated, in that you have two fundamentally different device types hung off the same interface. For our purposes, these are ATA disks and ATAPI devices. The NetBSD approach creates an 'atapibus', off which ATAPI devices are hung. These are registered with their SCSI layer, whilst IDE disks are associated with their 'wd' driver. I'm not sure if you're suggesting that the IDE interface should be parallelled with the SCSI interface, or whether you mean that the ATAPI interface should be treated as though it were another SCSI adapter. Perhaps the CAM docco will make things clearer. mike
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