Re: [PATCH net-next v4] openvswitch: enable NSH support

The second member of the union should be a variable length array [] of
struct nsh_md2_tlv

struct nsh_hdr {
    ovs_be16 ver_flags_ttl_len;
    uint8_t mdtype;
    uint8_t np;
    ovs_16aligned_be32 path_hdr;
    union {
        struct nsh_md1_ctx md1;
        struct nsh_md2_tlv md2[];
    };
};

That was the original design before Ben removed it due to missing support
in Microsoft compiler.
For the Kernel datapath we should go back to that.

I wonder about the possible 16-bit alignment of the 32-bit fields, though.
How is that handled in the kernel? Also struct nsh_md1_ctx has 32-bit
members, which might not be 32-bit aligned in the packet.

One afterthought: 

I think it would be good to add another member to the union to represent unstructured context headers as used, e.g., in the context of push_nsh.

struct nsh_hdr {
    ovs_be16 ver_flags_ttl_len;
    uint8_t mdtype;
    uint8_t np;
    ovs_16aligned_be32 path_hdr;
    union {
        uint8_t ctx_headers[];
        struct nsh_md1_ctx md1;
        struct nsh_md2_tlv md2[];
    };
};