Netlink is a network protocol that is used to communicate between the kernel and the userspace. For example, iproute use netlink in order to configure the network stack (interfaces, addresses, routes, etc). It is also used by the kernel to report hotplug events to the userland. The goal here is to add support in strace to decode netlink packet structures in order to be able to debug and discover netlink messages.
In 2016, the base ground work was done, now it can be extended to support more netlink family protocols.