Re: [PATCH bpf-next v6 0/8] resolve_btfids: Support for BTF modifications

[Alan Maguire <alan.maguire@oracle.com>]

On 19/12/2025 01:59, Ihor Solodrai wrote:
> This series changes resolve_btfids and kernel build scripts to enable
> BTF transformations in resolve_btfids. Main motivation for enhancing
> resolve_btfids is to reduce dependency of the kernel build on pahole
> capabilities [1] and enable BTF features and optimizations [2][3]
> particular to the kernel.
> 
> Patches #1-#4 in the series are non-functional changes in
> resolve_btfids.
> 
> Patch #5 makes kernel build notice pahole version changes between
> builds.
> 
> Patch #6 changes minimum version of pahole required for
> CONFIG_DEBUG_INFO_BTF to v1.22
> 
> Patch #7 makes a small prep change in selftests/bpf build.
> 
> The last patch (#8) makes significant changes in resolve_btfids and
> introduces scripts/gen-btf.sh. See implementation details in the patch
> description.
> 
> Successful BPF CI run: https://github.com/kernel-patches/bpf/actions/runs/20353330265
>

Thanks for this; in particular patch 5 is a great help! I verified that
changing pahole version (without running "make oldconfig") results in updates
to the CONFIG_PAHOLE_VERSION etc. Feel free to add for the series

Tested-by: Alan Maguire <alan.maguire@oracle.com>
 
> [1] https://lore.kernel.org/dwarves/ba1650aa-fafd-49a8-bea4-bdddee7c38c9@linux.dev/
> [2] https://lore.kernel.org/bpf/20251029190113.3323406-1-ihor.solodrai@linux.dev/
> [3] https://lore.kernel.org/bpf/20251119031531.1817099-1-dolinux.peng@gmail.com/
> 
> ---
> 
> v5->v6:
>   - patch #8: fix double free when btf__distill_base fails (reported by AI)
>     https://lore.kernel.org/bpf/e269870b8db409800045ee0061fc02d21721e0efadd99ca83960b48f8db7b3f3@mail.kernel.org/
> 
> v5: https://lore.kernel.org/bpf/20251219003147.587098-1-ihor.solodrai@linux.dev/
> 
> v4->v5:
>   - patch #3: fix an off-by-one bug (reported by AI)
>     https://lore.kernel.org/bpf/106b6e71bce75b8f12a85f2f99e75129e67af7287f6d81fa912589ece14044f9@mail.kernel.org/
>   - patch #8: cleanup GEN_BTF in Makefile.btf
> 
> v4: https://lore.kernel.org/bpf/20251218003314.260269-1-ihor.solodrai@linux.dev/
> 
> v3->v4:
>   - add patch #4: "resolve_btfids: Always build with -Wall -Werror"
>   - add patch #5: "kbuild: Sync kconfig when PAHOLE_VERSION changes" (Alan)
>   - fix clang cross-compilation (LKP)
>     https://lore.kernel.org/bpf/cecb6351-ea9a-4f8a-863a-82c9ef02f012@linux.dev/
>   - remove GEN_BTF env variable (Andrii)
>   - nits and cleanup in resolve_btfids/main.c (Andrii, Eduard)
>   - nits in a patch bumping minimum pahole version (Andrii, AI)
> 
> v3: https://lore.kernel.org/bpf/20251205223046.4155870-1-ihor.solodrai@linux.dev/
> 
> v2->v3:
>   - add patch #4 bumping minimum pahole version (Andrii, Alan)
>   - add patch #5 pre-fixing resolve_btfids test (Donglin)
>   - add GEN_BTF var and assemble RESOLVE_BTFIDS_FLAGS in Makefile.btf (Alan)
>   - implement --distill_base flag in resolve_btfids, set it depending
>     on KBUILD_EXTMOD in Makefile.btf (Eduard)
>   - various implementation nits, see the v2 thread for details (Andrii, Eduard)
> 
> v2: https://lore.kernel.org/bpf/20251127185242.3954132-1-ihor.solodrai@linux.dev/
> 
> v1->v2:
>   - gen-btf.sh and other shell script fixes (Donglin)
>   - update selftests build (Donglin)
>   - generate .BTF.base only when KBUILD_EXTMOD is set (Alan)
>   - proper endianness handling for cross-compilation
>   - change elf_begin mode from ELF_C_RDWR_MMAP to ELF_C_READ_MMAP_PRIVATE
>   - remove compressed_section_fix()
>   - nit NULL check in patch #3 (suggested by AI)
> 
> v1: https://lore.kernel.org/bpf/20251126012656.3546071-1-ihor.solodrai@linux.dev/
> 
> Ihor Solodrai (8):
>   resolve_btfids: Rename object btf field to btf_path
>   resolve_btfids: Factor out load_btf()
>   resolve_btfids: Introduce enum btf_id_kind
>   resolve_btfids: Always build with -Wall -Werror
>   kbuild: Sync kconfig when PAHOLE_VERSION changes
>   lib/Kconfig.debug: Set the minimum required pahole version to v1.22
>   selftests/bpf: Run resolve_btfids only for relevant .test.o objects
>   resolve_btfids: Change in-place update with raw binary output
> 
>  Documentation/scheduler/sched-ext.rst         |   1 -
>  MAINTAINERS                                   |   1 +
>  Makefile                                      |   9 +-
>  init/Kconfig                                  |   2 +-
>  lib/Kconfig.debug                             |  13 +-
>  scripts/Makefile.btf                          |  21 +-
>  scripts/Makefile.modfinal                     |   5 +-
>  scripts/Makefile.vmlinux                      |   2 +-
>  scripts/gen-btf.sh                            | 157 ++++++++
>  scripts/link-vmlinux.sh                       |  42 +-
>  tools/bpf/resolve_btfids/Makefile             |   3 +-
>  tools/bpf/resolve_btfids/main.c               | 358 ++++++++++++------
>  tools/sched_ext/README.md                     |   1 -
>  tools/testing/selftests/bpf/.gitignore        |   3 +
>  tools/testing/selftests/bpf/Makefile          |  11 +-
>  .../selftests/bpf/prog_tests/resolve_btfids.c |   4 +-
>  16 files changed, 443 insertions(+), 190 deletions(-)
>  create mode 100755 scripts/gen-btf.sh
>