On 2020-11-06 12:30 p.m., Jason Gunthorpe wrote: >> I certainly can't make decisions for code that isn't currently >> upstream. > > The rdma drivers are all upstream, what are you thinking about? Really? I feel like you should know what I mean here... I mean upstream code that actually uses the APIs that I'd have to introduce. I can't say here's an API feature that no code uses but the already upstream rdma driver might use eventually. It's fairly easy to send patches that make the necessary changes when someone adds a use of those changes inside the rdma code. >> Ultimately, if you aren't using the genpool you will have to implement >> your own mmap operation that somehow allocates the pages and your own >> page_free hook. > > Sure, the mlx5 driver already has a specialized alloctor for it's BAR > pages. So it *might* make sense to carve out a common helper to setup a VMA for P2PDMA to do the vm_flags check and set VM_MIXEDMAP... but besides that, there's no code that would be common to the two cases. >> I also don't expect this to be going upstream in the near term so don't >> get too excited about using it. > > I don't know, it is actually not that horrible, the GUP and IOMMU > related changes are simpler than I expected I think the deal breaker is the SGL hack and the fact that there are important IOMMU implementations that won't have support. Logan
