Date: Sun, 23 Nov 2008 15:40:03 GMT From: Marius Strobl <marius@alchemy.franken.de> To: freebsd-net@FreeBSD.org Subject: Re: kern/128833: [bge] Network packets corrupted when bge card is in 64-bit PCI slot Message-ID: <200811231540.mANFe3Dt098312@freefall.freebsd.org>
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The following reply was made to PR kern/128833; it has been noted by GNATS. From: Marius Strobl <marius@alchemy.franken.de> To: David Christensen <davidch@broadcom.com> Cc: bug-followup@FreeBSD.org Subject: Re: kern/128833: [bge] Network packets corrupted when bge card is in 64-bit PCI slot Date: Sun, 23 Nov 2008 16:34:59 +0100 On Mon, Nov 17, 2008 at 11:37:19AM -0800, David Christensen wrote: > > Ok, thanks for testing anyway. > > I still think that this isn't really a driver bug though but > > you are hitting some hardware-related problem like f.e. a > > silicon bug and the question is how to work around it. > > There is a documented errata for the 5701 A3 where a 64bit DMA > read can be terminated early by the bridge and then completed > later as a 32bit access, causing corruption on the 5701. The > errata states this type of behavior is rare in bridges and that > the workaround is to force 32bit operation (set bit 15 of register > 0x6800). It's not clear whether this errata is occurring without > seeing a but trace but it certainly sounds right. The only > question would be knowing "when" to force 32bit operation. Should > it be done in all cases or only for this bridge? > David, could it be that bug doesn't only affect 5701 A3 but also B3 (i.e. chipid 0x01050000) as in this case or even all 5701 revisions? How does the problem you describe relate to the 5701 PCI-X issue, which we align the RX buffer differently for as a workaround, would that problem also be avoided by limiting 5701 to 32-bit operations? Or is the A3-errata you described an entirely different issue and limited to 5701 in a 64-bit non-PCI-X slot, or would 5701 in a PCI-X slot even require both workarounds? Marius
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