What:           /sys/module/xen_blkfront/parameters/max
  Date:           June 2013
  KernelVersion:  3.11
  Contact:        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
  Description:
                  Maximum number of segments that the frontend will negotiate
                  with the backend for indirect descriptors. The default value
                  is 32 - higher value means more potential throughput but more
                  memory usage. The backend picks the minimum of the frontend
                  and its default backend value.