CX-4 SR-IOV on ROMED8-2T not working

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Active Member
Feb 26, 2018
My ASRock Rack EPYCD8 gave up the ghost and I replaced it with a ROMED8-2T. After replacing the motherboard I can't get SR-IOV working for my CX-4. It used to work just fine. The only difference is the motherboard, everything else is unchanged. SR-IOV works just fine for the onboard Intel X550-AT2 10GbE NIC so I know IOMMU and SR-IOV are enabled.

The /sys/.../sriov_totalvfs file reports 16, which is correct. When I try echo 16 > sriov_numvfs (or any other number) I get this:

mlx5_core 0000:c1:00.0: mlx5_cmd_out_err:779:(pid 1852): QUERY_HCA_CAP(0x100) op_mod(0x40) failed, status bad parameter(0x3), syndrome (0x5add95), err(-22)
mlx5_core 0000:c1:00.0: mlx5_device_enable_sriov:82:(pid 1852): failed to enable eswitch SRIOV (-22)
mlx5_core 0000:c1:00.0: mlx5_sriov_enable:168:(pid 1852): mlx5_device_enable_sriov failed : -22
The problem has to be a bios setting... but I haven't any guess as to which one. Help!