On 25/10/2024 17:19, Alexei Starovoitov wrote: > On Fri, Oct 25, 2024 at 9:15 AM Alan Maguire <alan.maguire@xxxxxxxxxx> wrote: >> >> On 25/10/2024 17:09, Alexei Starovoitov wrote: >>> On Thu, Oct 24, 2024 at 4:26 PM Andrii Nakryiko >>> <andrii.nakryiko@xxxxxxxxx> wrote: >>>> >>>>> >>>>> The good news is that already happens, provided you have the updated >>>>> pahole to handle distilled base generation. After building selftests I see >>>>> >>>>> $ objdump -h bpf_testmod.ko |grep BTF >>>>> 7 .BTF_ids 000001c8 0000000000000000 0000000000000000 00002c50 >>>>> 2**0 >>>>> 50 .BTF 000036f4 0000000000000000 0000000000000000 0006e048 >>>>> 2**0 >>>>> 51 .BTF.base 000004cc 0000000000000000 0000000000000000 0007173c >>>>> 2**0 >>>>> >>>> >>>> Indeed, after updating to the latest pahole master now I get >>>> .BTF.base, very nice. >>> >>> I pulled the latest pahole, rebuilt everything, >>> but still cannot get it to generate BTF.base. >>> >>> Any special trick needed? >> >> Hmm, should just work for bpf_testmod.ko as long as "pahole >> --supported_btf_features" reports "distilled_base" among the set of >> features. scripts/Makefile.btf should add that feature if KBUILD_EXTMOD >> is set, as it should be in the case of building bpf_testmod.ko. I'll >> double-check at my end with latest bpf-next, but it was working >> yesterday for me. > > There must be something else necessary: > > pahole -J -j --btf_features=encode_force,var,float,enum64,decl_tag,type_tag,optimized_func,consistent_func,decl_tag_kfuncs > --lang_exclude=rust --btf_features=distilled_base --btf_base vmlinux > .../bpf/bpf_testmod/bpf_testmod.ko; .../resolve_btfids -b vmlinux > .../selftests/bpf/bpf_testmod/bpf_testmod.ko; > > objdump -h .../testing/selftests/bpf/bpf_testmod/bpf_testmod.ko|grep BTF > 7 .BTF_ids 000001c8 0000000000000000 0000000000000000 00001d94 2**0 > 50 .BTF 00002ea7 0000000000000000 0000000000000000 00062e30 2**0 > Not sure what's going on for you here to be honest. I just tried pulling latest bpf-next and dwarves master branch, rebuilding pahole and selftests. I see .BTF.base sections for each .ko in selftests/bpf. Can you provide the output of pahole --supported_btf_features ? If it contains distilled_base things _should_ be working. The only other reason I can think of that you might not get .BTF.base sections is if dwarves was built against a local libbpf (rather than the git submodule) or local libbpf headers _and_ that libbpf did not include distilled base BTF support; in that case we skip .BTF.base generation since the APIs are not available.
