Date: Wed, 15 Sep 1999 01:39:48 -0700 (PDT) From: Matthew Jacob <mjacob@feral.com> To: Don Lewis <Don.Lewis@tsc.tdk.com> Cc: Andrew Gallatin <gallatin@cs.duke.edu>, "Justin T. Gibbs" <gibbs@caspian.plutotech.com>, scsi@FreeBSD.ORG, anderson@cs.duke.edu Subject: Re: data corruption when using aic7890 Message-ID: <Pine.BSF.4.05.9909150137590.6465-100000@semuta.feral.com> In-Reply-To: <199909150836.BAA17105@salsa.gv.tsc.tdk.com>
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> On Sep 15, 1:21am, Matthew Jacob wrote: > } Subject: Re: data corruption when using aic7890 > } > } > I wonder if it might be botching PCI MWI transactions. Is there a way > } > to get this beast to just use plain PCI Memory Write transactions (with > } > the obvious performance penalty)? > } > } Umm- can't you clear the INVAL bit in the PCI command register? See > } ahc_pci_attach where it enables BUS mastering.. > > Yeah, I forgot that this was a standard bit in the PCI command register. > According to the PCI spec it should already default to being off after > reset (unless the BIOS is enabling it). It looks like the driver > currently doesn't touch it. > > It would be an interesting experiment to see what this bit is set to > and to turn it off it is on. Maybe this can even be done from the BIOS > setup ... Or do it in the driver. Now that I think about it, I could easily imagine massive breakage for unaligned transfers if Adaptec pooched it by assuming MWI would be always enabled by drivers . -matt To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-scsi" in the body of the message
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