Messages in this thread | | | Date | Tue, 2 May 2006 14:35:07 +0100 | From | Christoph Hellwig <> | Subject | Re: [PATCH 5 of 13] ipath - use proper address translation routine |
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On Mon, May 01, 2006 at 12:00:00PM -0700, Roland Dreier wrote: > Arjan> do you really NEED the vaddr? (most of the time linux > Arjan> drivers don't need it, while other OSes do) If you really > Arjan> need it you should grab it at dma_map time ... (and > Arjan> realize that it's not kernel addressable per se ;) > > Yes, they need some kind of vaddr. > > It's kind of a layering problem. The IB stack assumes that IB devices > have a DMA engine that deals with bus addresses. But the ipath driver > has to simulate this by using a memcpy on the CPU to move data to the > PCI device. > > I really don't know what the right solution is. Maybe having some way > to override the dma mapping operations so that the ipath driver can > keep the info it needs?
Or stop doing the dma mapping in the IB upper level drivers. I told you that we'll get broken hardware that doesn't want dma mapping in the upper level driver, and pathscale created exactly that :)
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