On 2/4/20 2:56 PM, Toke Høiland-Jørgensen wrote: >> I'm confused, honestly. libbpf is either a dependency and thus can be >> relied upon to be present in the target system, or it's not and this >> whole dance with detecting libbpf presence needs to be performed. > > Yes, and iproute2 is likely to be built in both sorts of environments, > so we will have to support both :) > >> If libbpf is optional, then I don't see how iproute2 BPF-related code >> and complexity can be reduced at all, given it should still support >> loading BPF programs even without libbpf. Furthermore, given libbpf >> supports more features already and will probably be outpacing >> iproute2's own BPF support in the future, some users will start >> relying on BPF features supported only by libbpf "backend", so >> iproute2's own BPF backend will just fail to load such programs, >> bringing unpleasant surprises, potentially. So I still fail to see how >> libbpf can be optional and what benefit does that bring. > > I wasn't saying that libbpf itself should be optional; if we're porting > things, we should rip out as much of the old code as we can. I just > meant that we should support both modes of building, so distros that > *do* build libbpf as a library can link iproute2 against that with as > little friction as possible. > > I'm dead set on a specific auto-detection semantic either; I guess it'll > be up to the iproute2 maintainers whether they prefer defaulting to one > or the other. > A few concerns from my perspective: 1. Right now ip comes in around 650k unstripped; libbpf.a for 0.0.7 is around 1.2M with the size of libbpf.o > than ip. Most likely, making iproute2 use libbpf statically is going to be challenging and I am not sure it is the right thing to do (unless the user is building a static version of iproute2 commands). 2. git submodules can be a PITA to deal with (e.g., jumping between branches and versions), so there needs to be a good reason for it. 3. iproute2 code needs to build for a wide range of OSes and not lose functionality compared to what it has today.
