On Sun 15-10-17 08:58:56, Pavel Machek wrote: > Hi! > > > 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. > > So you'd suggest using ioctl() for allocating memory? Why not using standard mmap on the device fd? > That sounds quite ugly to me... mmap(MAP_CONTIG) is not nice, either, but better than > each driver inventing custom interface... As already pointed out elsewhere, I do not really see a different to remap_pfn_range from the API point of view. A driver has some requirements to the memory so those can be reflected in the mmap implementation for the driver. I really do not see how that would be a general interface without a lot of headache in future. Contiguous memory is a hard requirement to guarantee or give out without risks. -- Michal Hocko SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
