Date: Mon, 24 Jun 2002 15:09:33 -0700 (PDT) From: Matthew Jacob <mjacob@feral.com> To: Peter Wemm <peter@wemm.org> Cc: Andrew Gallatin <gallatin@cs.duke.edu>, "M. Warner Losh" <imp@village.org>, ticso@cicely.de, alpha@FreeBSD.ORG Subject: Re: Wither the nexus driver? Message-ID: <Pine.BSF.4.21.0206241503350.83773-100000@beppo> In-Reply-To: <20020624192143.D220C380E@overcee.wemm.org>
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On Mon, 24 Jun 2002, Peter Wemm wrote: > Matthew Jacob wrote: > > > > note that on 8X00 and 4100 systems that the PCI chipset is *not* the root > > nexus (or shouldn't be) > [..] > > This is has always been a peeve of mine about *BSD usage of root 'nexus'- the > > assumption that the PCI chipset is the one and only nexus. > > Logically, shouldn't the "nexus" be the cpu's backplane? > > ie: > root -> cpu -> nexus -+-> hostpci -> .... > +-> otherbus etc > A CPU is just another peripheral. The system nexus is, at least to my understanding, the main system interconnect that all major components tie into. If you have to have a tree representation, root == nexus. So, root/nexus -> cpu -> memory -> iobus So, whatever the "MAIN SYSTEM INTERCONNECT" is would be the system nexus. For 8X00 systems, it's the TLSB. For PCs it really probably really *is* the motherboard PCI/memory controller chipset (i.e., PIIIX). On SparcStation 1 it was the memory/SBus ASIC. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-alpha" in the body of the message
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