Netdev private dataroom for 6lowpan interfaces: All 6lowpan able net devices, means all interfaces with ARPHRD_6LOWPAN, must have "struct lowpan_priv" placed at beginning of netdev_priv. The priv_size of each interface should be calculate by: dev->priv_size = LOWPAN_PRIV_SIZE(LL_6LOWPAN_PRIV_DATA); Where LL_PRIV_6LOWPAN_DATA is sizeof linklayer 6lowpan private data struct. To access the LL_PRIV_6LOWPAN_DATA structure you can cast: lowpan_priv(dev)-priv; to your LL_6LOWPAN_PRIV_DATA structure. Before registering the lowpan netdev interface you must run: lowpan_netdev_setup(dev, LOWPAN_LLTYPE_FOOBAR); wheres LOWPAN_LLTYPE_FOOBAR is a define for your 6LoWPAN linklayer type of enum lowpan_lltypes. Example to evaluate the private usually you can do: static inline struct lowpan_priv_foobar * lowpan_foobar_priv(struct net_device *dev) { return (struct lowpan_priv_foobar *)lowpan_priv(dev)->priv; } switch (dev->type) { case ARPHRD_6LOWPAN: lowpan_priv = lowpan_priv(dev); /* do great stuff which is ARPHRD_6LOWPAN related */ switch (lowpan_priv->lltype) { case LOWPAN_LLTYPE_FOOBAR: /* do 802.15.4 6LoWPAN handling here */ lowpan_foobar_priv(dev)->bar = foo; break; ... } break; ... } In case of generic 6lowpan branch ("net/6lowpan") you can remove the check on ARPHRD_6LOWPAN, because you can be sure that these function are called by ARPHRD_6LOWPAN interfaces.