Messages in this thread | | | Date | Fri, 1 Jun 2007 22:26:01 +0200 | From | Andi Kleen <> | Subject | Re: [PATCH] quiet down swiotlb warnings |
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On Fri, Jun 01, 2007 at 04:20:38PM -0400, Rik van Riel wrote: > Andi Kleen wrote: > >On Fri, Jun 01, 2007 at 01:00:49PM -0700, Andrew Vasquez wrote: > >>yes, the card can support 64bit DMA transfers. but in this case the > >>'required' DMA mask returned from dma_get_required_mask() states that a > >>32bit mask would suffice. > > > >That's a bug in the kernel then that needs to be fixed. Find out > >why it does that and change it. Don't fix the symptoms, fix the root cause. > > The system in question only has 2GB of memory. > > Why would it need to do 64 bit DMA?
It doesn't. But it definitely doesn't need swiotlb either.
Normally swiotlb doesn't even try to bounce when dma mask is <= end_pfn so something must be very wrong in your kernel. It definitely isn't a mainline kernel. If this happens in Xen then Xen just needs fixing -- it should not try to bounce when the normal kernel wouldn't.
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