Re: [PATCHv2 iproute2-next 0/5] iproute2: add libbpf support

[David Ahern <dsahern@gmail.com>]

On 10/28/20 8:06 PM, Hangbin Liu wrote:
> On Wed, Oct 28, 2020 at 05:02:34PM -0600, David Ahern wrote:
>> fails to compile on Ubuntu 20.10:
>>
>> root@u2010-sfo3:~/iproute2.git# ./configure
>> TC schedulers
>>  ATM	yes
>>  IPT	using xtables
>>  IPSET  yes
>>
>> iptables modules directory: /usr/lib/x86_64-linux-gnu/xtables
>> libc has setns: yes
>> SELinux support: yes
>> libbpf support: yes
>> ELF support: yes
>> libmnl support: yes
>> Berkeley DB: no
>> need for strlcpy: yes
>> libcap support: yes
>>
>> root@u2010-sfo3:~/iproute2.git# make clean
>>
>> root@u2010-sfo3:~/iproute2.git# make -j 4
>> ...
>> /usr/bin/ld: ../lib/libutil.a(bpf_libbpf.o): in function `load_bpf_object':
>> bpf_libbpf.c:(.text+0x3cb): undefined reference to
>> `bpf_program__section_name'
>> /usr/bin/ld: bpf_libbpf.c:(.text+0x438): undefined reference to
>> `bpf_program__section_name'
>> /usr/bin/ld: bpf_libbpf.c:(.text+0x716): undefined reference to
>> `bpf_program__section_name'
>> collect2: error: ld returned 1 exit status
>> make[1]: *** [Makefile:27: ip] Error 1
>> make[1]: *** Waiting for unfinished jobs....
>> make: *** [Makefile:64: all] Error 2
> 
> You need to update libbpf to latest version.

nope. you need to be able to handle this. Ubuntu 20.10 was just
released, and it has a version of libbpf. If you are going to integrate
libbpf into other packages like iproute2, it needs to just work with
that version.

> 
> But this also remind me that I need to add bpf_program__section_name() to
> configure checking. I will see if I missed other functions' checking.

This is going to be an on-going problem. iproute2 should work with
whatever version of libbpf is installed on that system.