[PATCH 12/31] FreeBSD OFED support for DPDK MLX5 PMD
a) When enabling many VFs, the total amount of DMA mappings increase
significantly. This causes DMA allocations to take a lot of time
since they are serialized in the kernel.
As a result the driver enters into fatal condition due to
timeout and the system hangs. To recover from this we disable
MR cache for VFs. This also resolves Rx-Error MLX5 PMD issue.
PFs will still have a full cache and VFs cache can be manipulated
as usual after driver load.
b) The fast_registration length is used to convey length for memory
registrations through UMR which can be of any size up to 2^64.
Change the length type to be u64.