I built the current version of DPDK directly from dpdk.org after I
installed the current OFED Mellanox driver set:

* MLNX_OFED_LINUX-5.5-1.0.3.2-ubuntu20.04-x86_64.iso

with ./install --dpdk

I am using a Mellanox Technologies MT27710 Family [ConnectX-4 Lx] which is
Ethernet only; there is no IB mode for this NIC. This is a MT_2420110034
board. However, when I run dpdk-testpmd I see "No Verbs device matches PCI
device 0000:01:00.1, are kernel drivers loaded?"

EAL: Detected CPU lcores: 16
EAL: Detected NUMA nodes: 1
EAL: Detected static linkage of DPDK
EAL: Selected IOVA mode 'PA'
EAL: No free 2048 kB hugepages reported on node 0
EAL: VFIO support initialized
EAL: Probe PCI driver: mlx5_pci (15b3:1015) device: 0000:01:00.1 (socket 0)
mlx5_common: No Verbs device matches PCI device 0000:01:00.1, are kernel
drivers loaded?
mlx5_common: Verbs device not found: 01:00.1
mlx5_common: Failed to initialize device context.
EAL: Requested device 0000:01:00.1 cannot be used
EAL: Bus (pci) probe failed.

As far as I can see all the kernel modules are loaded:

lsmod | egrep "(ib|mlx)" | sort
ib_cm                  53248  2 rdma_cm,ib_ipoib
ib_core               368640  8
rdma_cm,ib_ipoib,iw_cm,ib_umad,rdma_ucm,ib_uverbs,mlx5_ib,ib_cm
ib_ipoib              135168  0
ib_umad                24576  0
ib_uverbs             139264  2 rdma_ucm,mlx5_ib
libahci                36864  1 ahci
libcrc32c              16384  2 btrfs,raid456
mlx5_core            1634304  1 mlx5_ib
mlx5_ib               397312  0
mlx_compat             69632  11
rdma_cm,ib_ipoib,mlxdevm,iw_cm,ib_umad,ib_core,rdma_ucm,ib_uverbs,mlx5_ib,ib_cm,mlx5_core
mlxdevm               172032  1 mlx5_core
mlxfw                  32768  1 mlx5_core
pci_hyperv_intf        16384  1 mlx5_core
psample                20480  1 mlx5_core
tls                    94208  2 bonding,mlx5_core

root@dc-c3-small-x86-01:~/Dev/reinvent/scripts# mst status -v
MST modules:
------------
    MST PCI module is not loaded
    MST PCI configuration module loaded
PCI devices:
------------
DEVICE_TYPE             MST                           PCI       RDMA
     NET                       NUMA
ConnectX4LX(rev:0)      /dev/mst/mt4117_pciconf0.1    01:00.1   mlx5_bond_0
    net-bond0                 -1

ConnectX4LX(rev:0)      /dev/mst/mt4117_pciconf0      01:00.0   mlx5_bond_0
    net-bond0                 -1