CO-RE supports

[navarrothiago]

References:

• libbpf-tools not building because clang attribute error iovisor/bcc#2855
• BPF portability and CO-RE
• Distro versions and BTF support aquasecurity/tracee#713

We can include a #define CORE to enable the inclusion for the system which supports CO:RE and disabled it for those which dont.
We need to pay attention, that the CO:RE doenst include the #define in the Linux header files.

[navarrothiago]

Networking application has a "stable interface". Could we assume that the interface (XDP metadata or struct xdp_md) will not change from one kernel to another. So, maybe the portability is already built in the actual solution. Is there any use case that this is not true? 🤔 Or for safety, do we assume that will change and use the CO-RE?