igb: remove M_HASHTYPE when RSS is not enabled

[cc]

Summary

manually cherry-pick efcc0423d80e

[kbowling]

Thanks. This matches i.e. http://iommu.com/datasheets/ethernet/controllers-nics/intel/e1000/ethernet-controller-i350-datasheet.pdf pg.313-314.

We can infer that igc needs a similar change based on lineage.

ixgbe uses the same hash function and nullification per http://iommu.com/datasheets/ethernet/controllers-nics/intel/ixgbe/333168-x540-datasheet-v3-1.pdf pg.290-291

I suspect this issue is now widespread in other drivers; M_HASHTYPE_OPAQUE and M_HASHTYPE_OPAQUE_HASH would only be suitable if the card is producing a unique but not tagged to one of the standard protocols (i.e. cxgb, ena are probably using it right, ixl, iavf, ice have one error).

[cc]

In D55143#1260913, @kbowling wrote:

Thanks. This matches i.e. http://iommu.com/datasheets/ethernet/controllers-nics/intel/e1000/ethernet-controller-i350-datasheet.pdf pg.313-314.

We can infer that igc needs a similar change based on lineage.

ixgbe uses the same hash function and nullification per http://iommu.com/datasheets/ethernet/controllers-nics/intel/ixgbe/333168-x540-datasheet-v3-1.pdf pg.290-291

I suspect this issue is now widespread in other drivers; M_HASHTYPE_OPAQUE and M_HASHTYPE_OPAQUE_HASH would only be suitable if the card is producing a unique but not tagged to one of the standard protocols (i.e. cxgb, ena are probably using it right, ixl, iavf, ice have one error).

I am afraid so. Maybe it's time to replace M_HASHTYPE_OPAQUE with M_HASHTYPE_NONE in default. I will bring this issue (together with the recently introduced sc_flowid) in Transport@.