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From: Terry Lambert <terry@cs.weber.edu>
Newsgroups: comp.periphs.scsi,comp.os.linux.hardware,comp.os.linux.setup,comp.unix.bsd.freebsd.misc
Subject: Re: SCSI diskIO
Date: 24 Aug 1995 02:53:14 GMT
Organization: Utah Valley State College, Orem, Utah
Lines: 39
Message-ID: <41gpiq$3h7@park.uvsc.edu>
References: <417ee7$1kp@trauma.rn.com> <419qu5$r4q@bonnie.tcd-dresden.de> <41fpji$g5a@overload.lbl.gov> <DDs7pM.KLA@ritz.mordor.com> <41g8re$11e@news.cloud9.net> <DDsDBK.45q@ritz.mordor.com>
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Xref: euryale.cc.adfa.oz.au comp.periphs.scsi:36224 comp.os.linux.hardware:14218 comp.os.linux.setup:18165 comp.unix.bsd.freebsd.misc:5064
ritz@ritz.mordor.com (Chris Mauritz) wrote:
] Thor Lancelot Simon (tls@cloud9.net) wrote:
] : >So if these things are so fast and so cheap, why not use them instead
] : >of something like the Buslogic 946C?
] :
] : There's not a whole lot of reason. The Buslogic will load the bus
] : less because it takes its commands out of local memory on the board
] : instead of by DMA from the host memory across the PCI bus. One could
] : concievably build an 810 board with local RAM to supply commands but that
] : would raise the price again.
] :
] : You also -- IMHO -- *don't* want to have to debug the NetBSD/FreeBSD
] : NCR driver if it breaks. It makes extensive use of self-modifying
] : code. In fact, both the code running on the host CPU and the code
] : running on the NCR modify the code that runs on the NCR. This is
] : unpleasant to contemplate.
]
] Ewwww...that sounds like a good enough reason for me.
You are probably mistaking the sequencer code for self-modifying
code. I don't see that in the driver sources on my machine.
Even if it did do that, it'd have to break for it to be a problem.
The driver is a finite state automaton, and as far as I know doesn't
have any way to get to bunged up states.
I don't know whether Linux uses the same NCR driver code as BSD
(I know the AIC 7770 code is mostly the same), but from my use on
my dual P90 system, I haven't seen any problems with the BSD NCR
driver whatsoever.
I would recommend it highly.
Terry Lambert
terry@cs.weber.edu
---
Any opinions in this posting are my own and not those of my present
or previous employers.