Messages in this thread | | | From | Andi Kleen <> | Subject | Re: X86_64 + VIA + 4g problems | Date | Mon, 2 Jan 2006 20:53:31 +0100 |
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On Monday 02 January 2006 20:18, Robert Hancock wrote: > Andi Kleen wrote: > > When you not compile in the SKGE network driver does everything else work? > > skge supports 64bit DMA, so it shouldn't use any IOMMU. > > Are you sure this is skge?
I grepped for the output in that badly truncated logfile and skge hit.
> Anyway, even if the driver does support > 64-bit DMA, I would be surprised if a desktop motherboard had the > Ethernet chip connected via a 64-bit PCI bus.
I meant 64bit DMA, aka double address cycle, not a 64bit wide PCI-X bus. That works on a 32bit PCI bus too. On modern boards it's likely PCI Express anyways for on board devices.
> > This brings up something I've been wondering. It's possible to run most > 64-bit capable PCI devices in a 32-bit slot (i.e. with the 64-bit part > hanging out of the slot). In this configuration the device will not be > able to use 64-bit DMA (unless it supports dual address cycle). However, > who is supposed to detect this and know to not try to use DMA addresses > above 4GB on that device?
64bit PCI-X bus has nothing to do with the addressing capability. It just gives you more bandwidth.
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