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Path: sserve!newshost.anu.edu.au!harbinger.cc.monash.edu.au!msuinfo!agate!howland.reston.ans.net!EU.net!Germany.EU.net!news.dfn.de!rrz.uni-koeln.de!RRZ.Uni-Koeln.DE!RRZ.Uni-Koeln.DE!news From: se@fileserv1.MI.Uni-Koeln.DE (Stefan Esser) Newsgroups: comp.os.386bsd.bugs Subject: FreeBSD: ASUS SP3G and writeback caches Date: 1 Sep 1994 16:28:15 GMT Organization: Institute of Nuclear Physics, University of Cologne, Germany Lines: 53 Distribution: world Message-ID: <344vevINN2t7j@rs1.rrz.Uni-Koeln.DE> NNTP-Posting-Host: fileserv1.mi.uni-koeln.de Keywords: FreeBSD Maybe something got broken in going from FreeBSD-1.1 to 1.1.5 ? There have been some reports on problems with the ASUS SP3G and the PCI SCSI driver, if the secondary cache has been configured for writeback operation. The PCI driver makes the NCR do lots of bus master operations to a data area that is written to by the CPU as well (command queues), and is the only FreeBSD driver so far, that depends on cache coherency for PCI to memory operations. The driver works with other chip sets and writeback caches, so it looks (at least in part) like a chip set (or documentation) problem . From reading the Intel Saturn chip set docs, I learned that the Saturn (as of Feb94) supports writeback only for either the primary or secondary cache. So I supposed that writeback might work with the DX2 (which has a writethrough primary cache), but not with the DX4, if its primary cache has already been set to writeback. I received a message that seemed to confirm that assumption, since a SP3G DX2 system with writeback enabled worked well. Under FreeBSD-1.1, that is ! Now the system has been upgraded to 1.1.5 and writeback had to be disabled to have it boot. Now I really would like to know, whether FreeBSD-1.1 would have allowed even the DX4 to work with a writeback secondary cache and the PCI SCSI driver. *** Is there anybody who can easily check that ? Since I don't have access to a Saturn rev. 4 data book, I'd like to know, whether that revision has support for writeback primary and secondary caches simultanously. *** Can anybody check that Saturn rev. 4 detail ? Have there been any changes that might affect cache handling between FreeBSD-1.1 and FreeBSD-1.1.5 ? Thanks in advance for any hints or facts. STefan -- Stefan Esser Internet: <se@ZPR.Uni-Koeln.DE> Zentrum fuer Paralleles Rechnen Tel: +49 221 4706010 Universitaet zu Koeln FAX: +49 221 4705160 Weyertal 80 50931 Koeln