nn_readb
nn_readb(nn, NFP_NET_CFG_BPF_ABI) == bpf->abi_version;
fw_mtu = nn_readb(nn, NFP_NET_CFG_BPF_INL_MTU) * 64 - 32;
max_stack = nn_readb(nn, NFP_NET_CFG_BPF_STACK_SZ) * 64;
cap = nn_readb(nn, NFP_NET_CFG_BPF_CAP);
max_stack = nn_readb(nn, NFP_NET_CFG_BPF_STACK_SZ) * 64;