On Fri, Oct 25, 2024 at 9:38 AM Alan Maguire <alan.maguire@xxxxxxxxxx> wrote: > > 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) That was it. I did 'git pull' in pahole instead of 'git pull --recurse-submodules'. Thanks for the tips. Now I see .BTF.base section.
