> We have done several rounds of discussion on linux-kernel about this so > far and the IB folks have not shown up to join in. I have tried to make > this as general as possible.
Sorry, this has been on my "things to look at" list for a while, but I haven't gotten a chance to really understand where things are yet. In general, this MMU notifier stuff will only be useful to a subset of InfiniBand/RDMA hardware. Some adapters are smart enough to handle changing the IO virtual -> bus/physical mapping on the fly, but some aren't. For the dumb adapters, I think the current ib_umem_get() is pretty close to as good as we can get: we have to keep the physical pages pinned for as long as the adapter is allowed to DMA into the memory region. For the smart adapters, we just need a chance to change the adapter's page table when the kernel/CPU's mapping changes, and naively, this stuff looks like it would work. Andrew, does that help? - R. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/