On Thu, 9 Sept 2021 at 10:26, Nicholas Brown wrote:
>
>
> On Thu, 9 Sept 2021 at 08:48, Benoit Ganne (bganne)
> wrote:
>
>> Hi Nick,
>>
>> > When attempting to build vpp against system libraries (dpdk, libbpf,
>> etc)
>> > on Debian Bullseye I get the following error when building the
>> > af_xdp_plugin.so
>> > Is the af_xdp plugin doing something unusual with libbpf?
>>
>> Af_xdp_plugin.so is a dynamically loadable object (as all VPP plugins),
>> hence libbpf.a must be compiled as PIC which is not the case here.
>> When you use VPP default build system, we compile libbpf.a as PIC and
>> link against that.
>>
>
> Hi Ben,
>
> Thanks for the tips.
>
> yes, I'd misread the debian build log for libbpf:
> https://buildd.debian.org/status/fetch.php?pkg=libbpf=amd64=0.3-2=1610313206=0
> Only the shared objects are build with PIC, the static library is not.
>
>
>> What is the reason to use the system libbpf instead of the one we
>> compile? Apart from PIC, libbpf itself is not stable yet so you could
>> encounter more subtile incompatibilities down the road.
>>
>>
> For the system I'm building I need the build to be reproducible and
> buildable in isolate. The layered vpp build system depends on downloading
> things from the internet during the build. The system will also be
> maintained for some time, so getting security updates for the likes of
> dpdk, libbpf, etc from the Debian system packages would also be important.
>
> The following change allows me to build:
>
> diff --git a/src/plugins/af_xdp/CMakeLists.txt
> b/src/plugins/af_xdp/CMakeLists.txt
> index cbe96aa59..ee1743bbe 100644
> --- a/src/plugins/af_xdp/CMakeLists.txt
> +++ b/src/plugins/af_xdp/CMakeLists.txt
> @@ -18,7 +18,7 @@ if (NOT BPF_INCLUDE_DIR)
> endif()
>
> set_property(GLOBAL PROPERTY FIND_LIBRARY_USE_LIB64_PATHS TRUE)
> -vpp_plugin_find_library(af_xdp BPF_LIB libbpf.a)
> +vpp_plugin_find_library(af_xdp BPF_LIB libbpf)
> vpp_plugin_find_library(af_xdp BPF_ELF_LIB elf)
> vpp_plugin_find_library(af_xdp BPF_Z_LIB z)
> if (NOT BPF_LIB OR NOT BPF_ELF_LIB OR NOT BPF_Z_LIB)
>
> but something that supports both a local or system library build would be
> preferable.
>
Actually I spoke too soon. :-) With this change it actually doesn't find
the library and thus simply doesn't build the plugin.
-- -- libbpf library not found - af_xdp plugin disabled
Thanks,
Nick
Separately, does the VPP cmake definitions allow me to configure which
> plugins are built (perhaps with some -D option), so I disable certain ones?
>
> Thanks,
> Nick
>
>
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