Stop opening xdp-dispatcher.o when LIBXDP_SKIP_DISPATCHER=1 is set

[ami-GS]

Even though LIBXDP_SKIP_DISPATCHER=1 is set, it still look for xdp-dispatcher.o and print stderror.

libxdp: Couldn't find a BPF file with name xdp-dispatcher.o
libxdp: Couldn't open BPF file xdp-dispatcher.o

Check the environment variable before opening file.

[tohojo]

This will break frags support when the environment variable is set, which is not a good idea. The xdp-dispatcher.o file is still needed even if the dispatcher is not used when loading things into the kernel.

[ami-GS]

You mean loading xdp-dispatcher.o is required to check capabilities even if LIBXDP_SKIP_DISPATCHER is set? It means that LIBXDP_OBJECT_PATHis also still needed withLIBXDP_SKIP_DISPATCHER`?

[tohojo]

Daiki AMINAKA ***@***.***> writes:

You mean loading xdp-dispatcher.o is required to check capabilities even if `LIBXDP_SKIP_DISPATCHER is set? It means that `LIBXDP_OBJECT_PATH` is also still needed with `LIBXDP_SKIP_DISPATCHER`?

Yes, unless you are statically linking the library, in which case the dispatcher object will be embedded into the binary itself.