What:           /sys/module/xen_blkfront/parameters/max_indirect_segments
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.

What:           /sys/module/xen_blkfront/parameters/feature_persistent
Date:           September 2020
KernelVersion:  5.10
Contact:        SeongJae Park <sj@kernel.org>
Description:
                Whether to enable the persistent grants feature or not.  Note
                that this option only takes effect on newly created frontends.
                The default is Y (enable).