On Mon, 2026-06-29 at 15:05 +0200, Jaipaul Cheernam wrote: > The kernel's Makefile.config has two BUILD_BPF_SKEL checks: > - Line 219: ifeq ($(BUILD_BPF_SKEL),1) - value check (works with =0) > - Line 668: ifdef BUILD_BPF_SKEL - defined check (triggers for ANY value) > > The previous fix (f48f6fb91c) passed BUILD_BPF_SKEL=0 which correctly > skips the first check but still triggers the second 'ifdef' check, > causing a build failure when clang is not available or too old. > > Change from: > PACKAGECONFIG[bpf-skel] = ",BUILD_BPF_SKEL=0" > To: > PACKAGECONFIG[bpf-skel] = "BUILD_BPF_SKEL=1," > > When bpf-skel is not in PACKAGECONFIG (the default), nothing is > passed to make and BUILD_BPF_SKEL remains undefined, which correctly > skips both checks. When enabled, BUILD_BPF_SKEL=1 is passed. > > Also move the PACKAGECONFIG entry to be grouped with the other > PACKAGECONFIG options for consistency. > > Signed-off-by: Jaipaul Cheernam <[email protected]>
Hi Jaipaul,
Based on the line numbers and conditionals you've put in the commit
message, I assume you're trying to build perf with a kernel source tree
that doesn't contain commit 9925495d96ef ("perf build: Default
BUILD_BPF_SKEL, warn/disable for missing deps") [1], i.e. before Linux
6.10.
[1]: https://git.kernel.org/torvalds/c/9925495d96efc14d885ba66c5696f664fe0e663c
The bpf-skel PACKAGECONFIG handling in master/wrynose appears to be
correct for kernel versions 6.10 and later. Unfortunately, there's no
single check that will work across all kernel versions:
- With Linux 6.9 & earlier,
BUILD_BPF_SKEL=1 -> enabled
BUILD_BPF_SKEL=0 -> enabled
BUILD_BPF_SKEL undef -> disabled
- With Linux 6.10 & later,
BUILD_BPF_SKEL=1 -> enabled
BUILD_BPF_SKEL=0 -> disabled
BUILD_BPF_SKEL undef -> enabled
I can't see any value that consistently disables that across all kernel
versions :(
So, you'll need to handle this appropriately depending on your kernel
version.
Best regards,
--
Paul Barker
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