Re: [PATCH bpf-next v1 4/4] selftests/bpf: Show the tag kflag in the raw BTF dump helper

[Eduard Zingerman <eddyz87@gmail.com>]

On Wed, 2026-09-16 at 18:20 -0700, Ihor Solodrai wrote:
> A kflag on BTF_KIND_DECL_TAG or BTF_KIND_TYPE_TAG means the tag string
> is an __attribute__ list rather than a btf_decl_tag()/btf_type_tag()
> argument. fprintf_btf_type_raw() did not print it, so a tag added with
> btf__add_decl_tag() and an attribute added with btf__add_decl_attr()
> dumped identically apart from their type IDs.
> 
> Print " kflag=1" for those two kinds, only when the flag is set, so no
> existing expected string changes.
> 
> Add a btf_write subtest for btf__add_decl_attr() and
> btf__add_type_attr().
> 
> Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
> ---

Acked-by: Eduard Zingerman <eddyz87@gmail.com>

> diff --git a/tools/testing/selftests/bpf/prog_tests/btf_write.c b/tools/testing/selftests/bpf/prog_tests/btf_write.c
> index 5c84723cf254..7ddda9348e4f 100644
> --- a/tools/testing/selftests/bpf/prog_tests/btf_write.c
> +++ b/tools/testing/selftests/bpf/prog_tests/btf_write.c
> @@ -606,6 +606,64 @@ static void test_btf_add_btf_split()
>  	btf__free(base);
>  }
>  
> +static void test_btf_attrs(void)
> +{
> +	const struct btf_type *t;
> +	struct btf *btf;
> +	int id;
> +
> +	btf = btf__new_empty();
> +	if (!ASSERT_OK_PTR(btf, "new_empty"))
> +		return;
> +
> +	id = btf__add_int(btf, "int", 4, BTF_INT_SIGNED);
> +	ASSERT_EQ(id, 1, "int_id");

Note: we have a set of utility macro BTF_*_ENC macros in test_btf.h,
      these are more convenient to use in some contexts.
      (At-least there is no need to assert every time).

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