On Fri, 2012-09-28 at 16:52 +0100, David Woodhouse wrote: > HP may have been shipping such things 'for a while' but it's never > actually worked right, yes? This thread is about the patch that's > intended to *fix* that?
I believe it currently works in non-passthrough mode since the RMRRs stick for that. It hasn't worked in passthrough mode since we disabled swiotlb and started kicking 32bit dma mask devices out of the si domain. It has probably never worked for VM usage if anyone has made the mistake of attempting that. > If they could just manage to make their firmware-owned DMA appear to > be from a different PCIe device/function from the one the OS gets to > own, that would make things "just work", right? Hell, their laptops > already have Ricoh multi-function devices that do their DMA from the > 'wrong' function.... take that concept and make it useful... > > If the DMA could be hidden from the IOMMU altogether, all the better. > But at least coming from its own dedicated devfn would avoid the > issues this patch attempts to solve. Hmm, an RMRR for a non-existent device would cause problems when we try to figure out the dma mask... if nothing else. The proposal seems to open pandora's box just a little further :-\ Maybe it would have to live outside of device ranges claimed by the DRHDs, but that implies physical topology changes. Thanks, Alex _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
