From owner-freebsd-scsi Sat Oct 9 4:41:10 1999 Delivered-To: freebsd-scsi@freebsd.org Received: from front7.grolier.fr (front7.grolier.fr [194.158.96.57]) by hub.freebsd.org (Postfix) with ESMTP id 486CC14C25 for ; Sat, 9 Oct 1999 04:40:55 -0700 (PDT) (envelope-from groudier@club-internet.fr) Received: from localhost (ppp-105-184.villette.club-internet.fr [194.158.105.184]) by front7.grolier.fr (8.9.3/No_Relay+No_Spam_MGC990224) with SMTP id NAA17493; Sat, 9 Oct 1999 13:40:48 +0200 (MET DST) Date: Sat, 9 Oct 1999 14:02:25 +0200 (MET DST) From: Gerard Roudier X-Sender: groudier@localhost To: "Matthew N. Dodd" Cc: Randell Jesup , scsi@FreeBSD.ORG Subject: Re: Driver for GDT6517RD RAID controller In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Sender: owner-freebsd-scsi@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org On Fri, 8 Oct 1999, Matthew N. Dodd wrote: > On 8 Oct 1999, Randell Jesup wrote: > > Nice results. I haven't played with 53c8xx chips, but I wrote some > > very fast drivers for the 53c7xx chips a long time ago ('93) for the > > Amiga. >=20 > I'd be interested in hearing your observation of the differences between > the 53c7xx and the 53c8xx chips as I'd really like to see the existing NC= R > driver support them. One year ago, I asked SYMBIOS about their opinion of having good support under Linux for 53c710 and later 7xx chips (basically the 720). They were absolutely not interested in this and even discouraged me to provide such support. The FreeBSD case should not be that different in this regard. In fact, the 7xx chips are only used nowadays as generic SCSI core for some intelligent controllers. > I suspect that all but the very early 53c700 and 710 chips would require > minimal changes. The 53c700 must be considered as having never existed. ;) About the 710 and later 7xx chips, speaking of a driver for this family does not make sense, since the system BUS stuff allows and requires proprietary implementations from the system hardware. Since it seems that machines that use on-board 7xx controllers are old, the needed documentation may just be no longer available. A driver that will separate system BUS code and SCSI core code may allow to support some set of 53c7xx based controllers. The 53c7xx support looks like that under Linux, for example. Basically, a SIM that supports 53c810 rev 1 can support 53c710 and later 53c7xx chips with minimal changes, provided that the BUS stuff be added or changed. The stock ncr driver supports the 53c810 rev 1, so starting from this code should be just fine for some 710 support.=20 No chance at all with the sym_hipd driver I am currently developping, since the aim of this driver is to take advantages of recent chips and PCI bus. Now, my 0.02 euro opinion about this topic: I am always been amazed by people who wants latest softwares to support old hardwares. If such compatibilty constraints had been always applied, may-be the fastest hardware nowadays would be a Z80 at 5 GigaHz and graphic would be some incredibly fast 16 colors VGA. ;-) Note that the poorness of latest IA32 arch we have to deal with may well be due to some backward compatibility + $$ issues. IMO, the 53c7xx parts are now material for history books and IT museums, and an O/S that does not provide support yet for these chips should not consider adding such a support, unless some driver magically be provided by some volonteer and be actually _maintained_.=20 G=E9rard. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message