Date: Sun, 13 Oct 2002 21:35:33 +0200 From: Bernd Walter <ticso@cicely8.cicely.de> To: Matthew Dillon <dillon@apollo.backplane.com> Cc: "M. Warner Losh" <imp@bsdimp.com>, tlambert2@mindspring.com, ticso@cicely.de, hch@infradead.org, wes@softweyr.com, vova@sw.ru, nate@root.org, arch@FreeBSD.org Subject: Re: Database indexes and ram Message-ID: <20021013193532.GC34517@cicely8.cicely.de> In-Reply-To: <200210131900.g9DJ0ZAM054777@apollo.backplane.com> References: <3DA954CF.98B0891A@mindspring.com> <20021013.060851.113437955.imp@bsdimp.com> <3DA9B4A8.194A02FC@mindspring.com> <20021013.120847.31902907.imp@bsdimp.com> <200210131900.g9DJ0ZAM054777@apollo.backplane.com>
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On Sun, Oct 13, 2002 at 12:00:35PM -0700, Matthew Dillon wrote: > Google is your friend. I found a quick reference on the PCI bus. > A 32 bit PCI bus can support 64 bit addresses through the use of > two address cycles prefacing the data transfer. The main problem is that it's not there since day 1. As Terry said - you need to know if the address path is 64 bit capable or not. E.g. the DEC 2105x PCI-PCI bridges can't do 64 bit, but the 2115x can. > That said, we all know how shoddy a large chunk of the PCI market is > (well, really the *entire* PC market, not just PCI). Just because the > spec allows it doesn't mean the chipset/motherboards support it or, > more importantly, support it reliably. Remember all the cache/MMU bugs > that showed up in the 486 series when people started actually using the > MMU? The same problem I currently see in getting 3.3V capable PCI cards. Sometimes reading the chip specs I get the feeling that vendors just forget to make that slit. > IMHO as much as I like the coolness of throwing more then 4G into a PC > not really designed to take more then 4G, I personally believe that > it is wiser to distribute processing at that point rather then spend > money on more specialized (and finicky) configurations. You will see > me throw more then 4G into a box when the next generation capable of > dealing with more then 4G becomes commoditized. Unless you can map PCI space you always have to deal with older PCI cards which are only capable of addressing 32 - no matter what platform and generation you are using. -- B.Walter COSMO-Project http://www.cosmo-project.de ticso@cicely.de Usergroup info@cosmo-project.de To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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