Date: Thu, 9 Nov 2000 16:59:50 +0000 (GMT) From: Terry Lambert <tlambert@primenet.com> To: gibbs@scsiguy.com (Justin T. Gibbs) Cc: winter@jurai.net (Matthew N. Dodd), peter@netplex.com.au (Peter Wemm), tlambert@primenet.com (Terry Lambert), wpaul@FreeBSD.ORG (Bill Paul), imp@village.org (Warner Losh), current@FreeBSD.ORG Subject: Re: vx driver patch Message-ID: <200011091659.JAA21072@usr08.primenet.com> In-Reply-To: <200011091502.eA9F25a86346@aslan.scsiguy.com> from "Justin T. Gibbs" at Nov 09, 2000 08:02:05 AM
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> >What about EISA/VL or EISA/PCI systems? > > What about them? PCI devices are supposed to be found via PCI configuration > space access. Even in these machines where a PCI card can be falsly > probed as an EISA card, the standard PCI configuration mechanism works > to correctly find PCI devices. VL cards are identified using ISA probe > techniques in all cases I'm aware of. It just turns out that the 2842 > uses a scheme that is very similar to that of an EISA card. As a backgrounder for other-than-Justin, Adaptec has a habit of making multipurpose ROMs that sit on different types of devices, so that they don't have to maintain multiple images. It's the EISA stuff in these ROMs that causes a non-EISA BIOS based EISA probe to incorrectly identify them as EISA. If I understand one of Justin's comments in this thread correctly, an additional layer is required for proper ordering, since he has a VLBUS device that shows up in the EISA BIOS based probe; this abstraction would be needed to allow the treatment to be uniform, instead of adding another "rogues" table to handle such things. I also seem to remember something about it being necessary to bouce buffers for the thing on a particular chipset (CMD?) where the address lines at 16M and above weren't properly bridged, so if it were misidentified as EISA, it would get very, very unhappy. My personal experience with EISA/PCI and EISA/ISA has been a net positive. I've never seen an EISA with VLBUS in the flesh, but I remember that they existed for a short while before PCI to let people use non-EISA video cards, because it was cheaper than an EISA video card of equal performance. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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