On Mon, 2015-11-02 at 22:48 +0000, David Woodhouse wrote: > > In the Intel case, the mapping setup is entirely per-device (except for > crap devices and devices behind a PCIe-PCI bridge, etc.). > > So you can happily have a passthrough mapping for *one* device, without > making that same mapping available to another device. You can make that > trade-off of speed vs. protection for each device in the system. Same for me. I should have written "in the context of a device ...", the problem reamains that it doesn't buy you much to do it *per -mapping* which is what this API seems to be about. > Currently we have the 'iommu=pt' option that makes us use passthrough > for *all* devices (except those whose dma_mask can't reach all of > physical memory). But I could live with something like Shamir is > proposing, which lets us do the bypass only for performance-sensitive > devices which actually *ask* for it (and of course we'd have a system- > wide mode which declines that request and does normal mappings anyway). > -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
