On Fri 13-10-17 10:42:37, Cristopher Lameter wrote: > On Fri, 13 Oct 2017, Michal Hocko wrote: > > > On Fri 13-10-17 10:20:06, Cristopher Lameter wrote: > > > On Fri, 13 Oct 2017, Michal Hocko wrote: > > [...] > > > > I am not really convinced this is a good interface. You are basically > > > > trying to bypass virtual memory abstraction and that is quite > > > > contradicting the mmap API to me. > > > > > > This is a standardized posix interface as described in our presentation at > > > the plumbers conference. See the presentation on contiguous allocations. > > > > Are you trying to desing a generic interface with a very specific and HW > > dependent usecase in mind? > > There is a generic posix interface that could we used for a variety of > specific hardware dependent use cases. Yes you wrote that already and my counter argument was that this generic posix interface shouldn't bypass virtual memory abstraction. > > > The contiguous allocations are particularly useful for the RDMA API which > > > allows registering user space memory with devices. > > > > then make those devices expose an implementation of an mmap which does > > that. You would get both a proper access control (via fd), accounting > > and others. > > There are numerous RDMA devices that would all need the mmap > implementation. And this covers only the needs of one subsystem. There are > other use cases. That doesn't prevent providing a library function which could be reused by all those drivers. Nothing really too much different from remap_pfn_range. -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
