Re: [PATCH bpf-next v4 5/8] kbuild: Sync kconfig when PAHOLE_VERSION changes

Andrii Nakryiko
2025-12-18T21:01:27Z

On Wed, Dec 17, 2025 at 4:34 PM Ihor Solodrai <ihor.solodrai@linux.dev> wrote:
>
> This patch implements kconfig re-sync when the pahole version changes
> between builds, similar to how it happens for compiler version change
> via CC_VERSION_TEXT.
>
> Define PAHOLE_VERSION in the top-level Makefile and export it for
> config builds. Set CONFIG_PAHOLE_VERSION default to the exported
> variable.
>
> Kconfig records the PAHOLE_VERSION value in
> include/config/auto.conf.cmd [1].
>
> The Makefile includes auto.conf.cmd, so if PAHOLE_VERSION changes
> between builds, make detects a dependency change and triggers
> syncconfig to update the kconfig [2].
>
> For external module builds, add a warning message in the prepare
> target, similar to the existing compiler version mismatch warning.
>
> Note that if pahole is not installed or available, PAHOLE_VERSION is
> set to 0 by pahole-version.sh, so the (un)installation of pahole is
> treated as a version change.
>
> See previous discussions for context [3].
>
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/scripts/kconfig/preprocess.c?h=v6.18#n91
> [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Makefile?h=v6.18#n815
> [3] https://lore.kernel.org/bpf/8f946abf-dd88-4fac-8bb4-84fcd8d81cf0@oracle.com/
>
> Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
> ---
> Makefile | 9 ++++++++-
> init/Kconfig | 2 +-
> 2 files changed, 9 insertions(+), 2 deletions(-)
>

This is great, we should have done that a long time ago :) …