On Fri, Oct 25, 2024 at 9:49 AM Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx> wrote: > > 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. Forgot to add that even in this broken configuration: before: $ pahole --supported_btf_features encode_force,var,float,decl_tag,type_tag,enum64,optimized_func,consistent_func,decl_tag_kfuncs,reproducible_build,distilled_base,global_var after: $ pahole --supported_btf_features encode_force,var,float,decl_tag,type_tag,enum64,optimized_func,consistent_func,decl_tag_kfuncs,reproducible_build,distilled_base,global_var No difference :( Both claim that distilled_base is working, but it didn't. Before had older libbpf submodule. Maybe it should print libbpf version or something ?
