Date: Tue, 4 Jul 2000 19:16:30 +0200 From: Gerhard Sittig <Gerhard.Sittig@gmx.net> To: freebsd-stable@FreeBSD.ORG Subject: Re: Dump takes ages on SCSI. (several times faster on IDE) Message-ID: <20000704191630.U5945@speedy.gsinet> In-Reply-To: <200007041222.FAA02795@mass.osd.bsdi.com>; from msmith@freebsd.org on Tue, Jul 04, 2000 at 05:22:36AM -0700 References: <20000703193834.Q5945@speedy.gsinet> <200007041222.FAA02795@mass.osd.bsdi.com>
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On Tue, Jul 04, 2000 at 05:22 -0700, Mike Smith wrote:
> >
> > The Problem with aha1542 (ISA busmaster capable controller)
> > in PCI boards is that it is located "at the end" of a long
> > chain to memory. Chances are, busmastering will not work at
> > all behind the PCI to ISA bridge since all the PCI devices
> > have higher priority and the ISA gadget never gets any access
> > granted or at least always too late. You're better off with
> > a PCI controller.
>
> This is Just Not True.
Can you please tell me more about it? I'm not sure of the
priority thing I mention above, but the fact that ISA busmaster
devices and PCI boards somewhat collide or counter operate
(sorry, lacking better words once more) is what I got from
serious papers here. How direct is the access method an ISA
controller has to the memory when sitting behind a bridge? I
would be glad to believe a 1542B/C in a PCI machine is A Good
Thing(TM). :)
virtually yours 82D1 9B9C 01DC 4FB4 D7B4 61BE 3F49 4F77 72DE DA76
Gerhard Sittig true | mail -s "get gpg key" Gerhard.Sittig@gmx.net
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