Alexei Starovoitov <ast@xxxxxxxxxx> writes: > The last few month BPF community has been discussing an approach to call > chaining, since exiting bpt_tail_call() mechanism used in production XDP > programs has plenty of downsides. The outcome of these discussion was a > conclusion to implement dynamic re-linking of BPF programs. Where rootlet XDP > program attached to a netdevice can programmatically define a policy of > execution of other XDP programs. Such rootlet would be compiled as normal XDP > program and provide a number of placeholder global functions which later can be > replaced with future XDP programs. BPF trampoline, function by function > verification were building blocks towards that goal. The patch 1 is a final > building block. It introduces dynamic program extensions. A number of > improvements like more flexible function by function verification and better > libbpf api will be implemented in future patches. This is great, thank you! I'll go play around with it; couldn't spot anything obvious from eye-balling the code, except that yeah, it does need a more flexible libbpf api :) One thing that's not obvious to me: How can userspace tell which programs replace which functions after they are loaded? Is this put into prog_tags in struct bpf_prog_info, or? For the series: Acked-by: Toke Høiland-Jørgensen <toke@xxxxxxxxxx> -Toke
