Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> writes: > On Thu, Oct 22, 2020 at 8:39 PM Hangbin Liu <haliu@xxxxxxxxxx> wrote: >> >> This patch converts iproute2 to use libbpf for loading and attaching >> BPF programs when it is available, which is started by Toke's >> implementation[1]. With libbpf iproute2 could correctly process BTF >> information and support the new-style BTF-defined maps, while keeping >> compatibility with the old internal map definition syntax. >> >> The old iproute2 bpf code is kept and will be used if no suitable libbpf >> is available. When using libbpf, wrapper code in bpf_legacy.c ensures that >> iproute2 will still understand the old map definition format, including >> populating map-in-map and tail call maps before load. >> >> In bpf_libbpf.c, we init iproute2 ctx and elf info first to check the >> legacy bytes. When handling the legacy maps, for map-in-maps, we create >> them manually and re-use the fd as they are associated with id/inner_id. >> For pin maps, we only set the pin path and let libbp load to handle it. >> For tail calls, we find it first and update the element after prog load. > > I never implemented tail call map initialization using the same > approach as declarative map-in-map support in libbpf, because no one > asked and/or showed a use case. But all the pieces are there, and if > there's interest, we should probably support that in libbpf as well. Yeah, that's what we figured; and since this series maintains compatibility with the old map definition format for declarative tail-calls, this doesn't have to hold up the conversion: iproute2 will just magically gain this when/if it lands in libbpf :) -Toke
