This flag is needed for compatibility with older versions of the virtio_blk library. Change-Id: I8243d51a39971dd37d0c65b29bd976b5b84978aa Signed-off-by: Seth Howell <seth.howell@intel.com> Reviewed-on: https://review.gerrithub.io/367612 Tested-by: SPDK Automated Test System <sys_sgsw@intel.com> Reviewed-by: Daniel Verkamp <daniel.verkamp@intel.com> Reviewed-by: Ben Walker <benjamin.walker@intel.com>