> but there are no evidence of,
nl-gen will only impact compile rather than configure, right?

Those above build time error will happen in upstream version if you only install libnl3 but libnl-genl-3 for libnl3 case.

But anyway, it shouldn't impact 'configure' action. 


2012/11/9 Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
On (11/09/12 19:17), Austin Zhang wrote:
>    libnl3:
>    libnl-3.0                      libnl - Convenience library for netlink
>    sockets
>    libnl2:
>    libnl-2.0                      libnl - Convenience library for netlink
>    sockets
>

so, libnl-3.0.pc and libnl-2.0.pc are there, but there are no evidence of, for example,
libnl-genl

pkg-config output on Arch

libnl-3.0                   libnl - Convenience library for netlink sockets
libnl-cli-3.0               libnl-cli - Command Line Interface library for netlink sockets
libnl-nf-3.0                libnl-nf - Netfilter Netlink Library
libnl-route-3.0             libnl-route - Netlink Routing Family Library
libnl-genl-3.0              libnl-genl - Generic Netlink Library


in case if we remove libnl-genl from PKG_CHECK_MODULES, we'll break the build, because LIBNL_LIBS
should be '-lnl-genl-3 -lnl-3', not just '-lnl-3'.

[..]
src/tuning/iw.c:89: undefined reference to `genl_connect'
src/tuning/iw.c:95: undefined reference to `genl_ctrl_alloc_cache'
src/tuning/iw.c:101: undefined reference to `genl_ctrl_search_by_name'
and so on...


looks like we need to workaround ubuntu.


        -ss