[PATCH bpf-next] scripts/gen-btf.sh: Fix .btf.o generation when compiling for RISCV

[PATCH bpf-next] scripts/gen-btf.sh: Fix .btf.o generation when compiling for RISCV

[Ihor Solodrai]

gen-btf.sh emits a .btf.o file with BTF sections to be linked into
vmlinux in link-vmlinux.sh

This .btf.o file is created by compiling an emptystring with ${CC},
and then adding BTF sections into it with ${OBJCOPY}.

To ensure the .btf.o is linkable when cross-compiling with LLVM, we
have to also pass ${KBUILD_FLAGS}, which in particular control the
target word size.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202512240559.2M06DSX7-lkp@intel.com/
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
---
 scripts/gen-btf.sh | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/gen-btf.sh b/scripts/gen-btf.sh
index 06c6d8becaa2..12244dbe097c 100755
--- a/scripts/gen-btf.sh
+++ b/scripts/gen-btf.sh
@@ -96,7 +96,7 @@ gen_btf_o()
 	# deletes all symbols including __start_BTF and __stop_BTF, which will
 	# be redefined in the linker script.
 	info OBJCOPY "${btf_data}"
-	echo "" | ${CC} ${CLANG_FLAGS} -c -x c -o ${btf_data} -
+	echo "" | ${CC} ${CLANG_FLAGS} ${KBUILD_CFLAGS} -c -x c -o ${btf_data} -
 	${OBJCOPY} --add-section .BTF=${ELF_FILE}.BTF \
 		--set-section-flags .BTF=alloc,readonly ${btf_data}
 	${OBJCOPY} --only-section=.BTF --strip-all ${btf_data}
-- 
2.52.0

Re: [PATCH bpf-next] scripts/gen-btf.sh: Fix .btf.o generation when compiling for RISCV

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to bpf/bpf-next.git (master)
by Alexei Starovoitov <ast@kernel.org>:

On Mon, 29 Dec 2025 12:28:23 -0800 you wrote:
> gen-btf.sh emits a .btf.o file with BTF sections to be linked into
> vmlinux in link-vmlinux.sh
> 
> This .btf.o file is created by compiling an emptystring with ${CC},
> and then adding BTF sections into it with ${OBJCOPY}.
> 
> To ensure the .btf.o is linkable when cross-compiling with LLVM, we
> have to also pass ${KBUILD_FLAGS}, which in particular control the
> target word size.
> 
> [...]

Here is the summary with links:
  - [bpf-next] scripts/gen-btf.sh: Fix .btf.o generation when compiling for RISCV
    https://git.kernel.org/bpf/bpf-next/c/600605853f87

You are awesome, thank you!
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