Re: [PATCH bpf-next 0/4] libbpf: add XDP binding support

[Daniel Borkmann]

On 01/20/2018 09:28 AM, Ãric Leblond wrote:
> Hi,
> 
> Le 20 janv. 2018 9:21 AM, Daniel Borkmann <daniel@xxxxxxxxxxxxx> a Ãcrit :
> 
>     On 01/20/2018 03:27 AM, Alexei Starovoitov wrote:
>      > On Sat, Jan 20, 2018 at 03:00:37AM +0100, Daniel Borkmann wrote:
>      >> On 01/19/2018 12:43 AM, Eric Leblond wrote:
>      >>> Hello,
>      >>>
>      >>> This patchset rebases the libbpf code on latest bpf-next code and
>     addresses
>      >>> remarks by Daniel.
>      >>
>      >> Ok, I think it's a good start. We should later on clean up the
>      >> netlink handling code a bit, but that's all internal and can be
>      >> done in a second step. Applied to bpf-next, thanks Eric.
>      >
>      > Sorry, Eric, Daniel.
>      > I had to revert this patch set. It breaks build on systems
>      > where headers are not the most recent.
> 
> Oops, sorry.
> 
>      > Since libbpf is used by perf it has to be built cleanly on centos7 at least.
>      >
>      > The errors I got:
>      > bpf.c: In function âbpf_set_link_xdp_fdâ:
>      > bpf.c:456:23: error: âSOL_NETLINKâ undeclared (first use in this function)
>      >   if (setsockopt(sock, SOL_NETLINK, NETLINK_EXT_ACK,
>      >                        ^~~~~~~~~~~
>      > bpf.c:456:23: note: each undeclared identifier is reported only once for
>     each function it appears in
>      > bpf.c:456:36: error: âNETLINK_EXT_ACKâ undeclared (first use in this
>     function)
>      >   if (setsockopt(sock, SOL_NETLINK, NETLINK_EXT_ACK,
>      >                                     ^~~~~~~~~~~~~~~
>      > nlattr.c: In function ânla_dump_errormsgâ:
>      > nlattr.c:152:34: error: âNLMSGERR_ATTR_MAXâ undeclared (first use in this
>     function)
>      >   struct nla_policy extack_policy[NLMSGERR_ATTR_MAX + 1] = {
> 
>     Yeah, fully agree, thanks for catching this, Alexei!
> 
> What's the recommended solution here ? Include some kernel tree files or define 
> constant if not defined ?

I think typical way is to pull such headers into tools/include/.

Cheers,
Daniel