Date: Mon, 29 Sep 1997 13:56:34 -0700 From: Julian Elischer <julian@whistle.com> To: MetcalJM@utrc.utc.com Cc: gibbs@FreeBSD.ORG, questions@FreeBSD.ORG Subject: Re: Q: Good learning documents for SCSI device drivers Message-ID: <34301602.167EB0E7@whistle.com> References: <95A2D2968BD9D011A38B00A0C95727DB27AB03@express2.res.utc.com>
next in thread | previous in thread | raw e-mail | index | archive | help
Hi, I wrote most of hte present SCSI system for FreeBSD, however it's been several years since I did that, and I've been working on other things. Thw adapters I wrote drivers fro were all "intelligent" adapters so I never really got into the "NEXUS" stuff. Basically the nexus is a particular pairing of a client and a requestor, for an operation.. I never got much more into it than that.. I can suggest you visit the following ftp site: ftp://ftp.symbios.com/pub/standards/io/ where you will find the SCSI standard and many ther related things. While I can give comments on how the present SCSI system is written, that will soon be a thing of the past. The present SCSI system was good for its day, but time has marched on and Justin (CC'd) is writing a new system based on the SCSI-CAM standard. This should allow us to meke better use of 3rd party CAM modules. Never-teh-less, if you have specific questions about the UPPER layers of the current SCSI system, feel free to ask (I may not know the answer however). There was a massive set of changes that went into it a couple of years ago that obfuscated a lot of what's going on behind MACROs which I was not happy with, and some of the structures changed function with time, and are there-for misleadingly named. I started several times on documents on how it fitted together but never got past the introduction. MetcalJM@utrc.utc.com wrote: > > Hello, > > I am writing to ask if anyone can point me to some good learning > documents for learning the basics of the SCSI subsystem. I have > an open problem with the gnats database > > http://www.freebsd.org/cgi/query-pr.cgi?pr=4498 > > where my Iomega Zip 100 SCSI drive atached to my ProAudioStudio > SCSI adapter is having data corruption problems. I have written > to both the FreeBSD and LINUX authors of the ncr5830 code and > have received no replies. I understand since few people actually > using FreeBSD use such hardware, I am probably on my own for a > fix. All I'm asking is some direction in finding good books > to learn from in order to solve the problem myself. I have > never written any kind of device driver, much less a driver > for a SCSI device. I have fairly good C programming skills > (ie, I can understand the logic flow of the ncr5830.c kernel > code and understand the definitions and usage syntax of the data > structures). But the code is otherwise meaningless to me > since I have no idea about how the code interacts with the > hardware (eg. what's "establising a nexus" mean?). I'm sure > there are plenty of great books out there where a motivated > person like myself can learn what he needs to know. > > I hope some kind soul can give me some focus. Understand > that I would need the basics, yet I would also need enough practical > focus, from whatever sources are suggested, to actually trouble-shoot > and hack into some real code. Ideally, literature that might cover > the ncr5830 would be great!! I understand this to be a well documented > and understood device. > > Thanks in advance for any help!! > > JM > ----------- > > > Jeffrey M. Metcalf > > Assistant Computer Systems Support Engineer > > United Technologies Research Center > > metcaljm@utrc.utc.com > > (860) 610-7576 > > > >
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?34301602.167EB0E7>