Date: Tue, 05 Nov 2002 22:12:08 -0800 From: Terry Lambert <tlambert2@mindspring.com> To: Dinesh Nair <dinesh@alphaque.com> Cc: Richard Sharpe <rsharpe@ns.aus.com>, Matt <mattl3@earthlink.net>, hackers@FreeBSD.ORG Subject: Re: max phy mem known working with FreeBSD 4.x Message-ID: <3DC8B2B8.C3A61C99@mindspring.com> References: <20021106115704.D340-100000@prophet.alphaque.com>
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Dinesh Nair wrote: > On Tue, 5 Nov 2002, Richard Sharpe wrote: > > Well, we have 4GB in a 4.6.2 system, and I think that we ran 4.3 on those > > systems for a while. > > > > However, you lose anywhere between 128M and 512M because of the PCI > > address space. > > what PCI address space ? could someone explain about this loss ? > curiousity beckons. :) Short answer ------------ Memory on devices on the PCI bus is mappes into the physical memory address space, and so "covers up" RAM in the window in which it is mapped. Good chipsets will only map in memory that actually exists for devices which are actually installed. Bad chipsets will reserve the entire window, and therefore take a much larger chunk out. Long answer ----------- See http://www.pcisig.com/specifications/ordering_information The CDROM and a full set of the specifications will run you US$1500, plus US$15 shipping in the US, or US$40 shipping, international. The price goes from $1500 to $75, if you can order through a company which is already a member of the PCI SIG. Your company can join the PCI SIG for a US$3000 per year fee, if it is not already a member. See http://www.pcisig.com/membership/join_pci_sig/new_member_forms/ for membership information. FWIW, I got my copy when I was an employeed of a member company; it's the way to go, if you can do it. -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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