On 11/4/20 3:21 AM, Daniel Borkmann wrote: > >> Then libbpf release process can incorporate proper testing of libbpf >> and iproute2 combination. >> Or iproute2 should stay as-is with obsolete bpf support. >> >> Few years from now the situation could be different and shared libbpf >> would >> be the most appropriate choice. But that day is not today. > > Yep, for libbpf to be in same situation as libelf or libmnl basically > feature > development would have to pretty much come to a stop so that even minor > or exotic > distros get to a point where they ship same libbpf version as major > distros where > then users can start to rely on the base feature set for developing > programs > against it. User experience keeps getting brought up, but I also keep reading the stance that BPF users can not expect a consistent experience unless they are constantly chasing latest greatest versions of *ALL* S/W related to BPF. That is not a realistic expectation for users. Distributions exist for a reason. They solve real packaging problems. As libbpf and bpf in general reach a broader audience, the requirements to use, deploy and even tryout BPF features needs to be more user friendly and that starts with maintainers of the BPF code and how they approach extensions and features. Telling libbpf consumers to make libbpf a submodule of their project and update the reference point every time a new release comes out is not user friendly. Similarly, it is not realistic or user friendly to *require* general Linux users to constantly chase latest versions of llvm, clang, dwarves, bcc, bpftool, libbpf, (I am sure I am missing more), and, by extension of what you want here, iproute2 just to upgrade their production kernel to say v5.10, the next LTS, or to see what relevant new ebpf features exists in the new kernel. As a specific example BTF extensions are added in a way that is all or nothing. Meaning, you want to compile kernel version X with CONFIG_DEBUG_INFO_BTF enabled, update your toolchain. Sure, you are using the latest LTS of $distro, and it worked fine with kernel version X-1 last week, but now compile fails completely unless the pahole version is updated. Horrible user experience. Again, just an example and one I brought up in July. I am sure there more. Linux APIs are about stability and consistency. Commands and libraries that work on v5.9 should work exactly the same on v5.10, 5.11, 5.12, ... *IF* I want a new feature (kernel, bpf or libbpf), then the requirement to upgrade is justified. But if I am just updating my kernel, or updating my compiler, or updating iproute2 because I want to try out some new nexthop feature, I should not be cornered into an all or nothing scheme.
