On Wed, Jul 24, 2019 at 10:06:22AM -0600, Logan Gunthorpe wrote: > Yes. This is the downside of dealing only with a phys_addr_t: we have to > look up against it. Unfortunately, I believe it's possible for different > BARs on a device to be in different windows, so something like this is > necessary unless we already know the BAR the phys_addr_t belongs to. It > might probably be sped up a bit by storing the offsets of each bar > instead of looping through all the bridge windows, but I don't think it > will get you *that* much. > > As this is an example with no users, the answer here will really depend > on what the use-case is doing. If they can lookup, ahead of time, the > mapping type and offset then they don't have to do this work on the hot > path and it means that pci_p2pdma_map_resource() is simply not a > suitable API. Ok. So lets just keep this out as an RFC and don't merge it until an actual concrete user shows up.
