kernel/Documentation/ABI/removed/net_dma

   1 What:           tcp_dma_copybreak sysctl
   2 Date:           Removed in kernel v3.13
   3 Contact:        Dan Williams <dan.j.williams@intel.com>
   4 Description:
   5         Formerly the lower limit, in bytes, of the size of socket reads
   6         that will be offloaded to a DMA copy engine.  Removed due to
   7         coherency issues of the cpu potentially touching the buffers
   8         while dma is in flight.