Re: [PATCH bpf-next v6 1/2] libbpf: support selective kernel module BTF loading via bpf_object_open_opts

[Fuyu Zhao <zhaofuyu@vivo.com>]

On 8/31/2026 10:46 PM, bot+bpf-ci@kernel.org wrote:
>> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
>> index b965ad5715403..1cabf7e465546 100644
>> --- a/tools/lib/bpf/libbpf.h
>> +++ b/tools/lib/bpf/libbpf.h
>> @@ -224,10 +224,32 @@ struct bpf_object_open_opts {
>>  	 * point (/sys/fs/bpf), in case this default behavior is undesirable.
>>  	 */
>>  	const char *bpf_token_path;
> 
> [ ... ]
> 
>> +	/*
>> +	 * Optional list of kernel module names whose BTFs should be loaded.
>> +	 * nr_btf_module_names specifies the number of entries in
>> +	 * btf_module_names.
>> +	 *
>> +	 * With btf_module_names:
>> +	 * - when provided, only the BTFs of the specified modules are loaded;
>> +	 * - when an empty list is provided, no module BTFs are loaded;
>> +	 * - when NULL, all module BTFs are loaded as before.
>> +	 *
>> +	 * The list must contain valid, non-empty module names and must not
>> +	 * contain duplicate entries; otherwise -EINVAL is returned.
>> +	 *
>> +	 * This affects:
>> +	 * - BPF CO-RE relocations against types defined in modules;
>> +	 * - BTF-based resolution of attach targets;
>> +	 * - module-qualified tracing multi-attach targets;
>> +	 * - struct_ops kernel type resolution;
>> +	 * - extern (ksym) resolution for kernel symbols defined in modules.
>> +	 */
>> +	const char **btf_module_names;
>> +	size_t nr_btf_module_names;
>                       ^^
> This isn't a bug, but would btf_module_cnt (or just cnt-style naming) fit
> better here? The other opts structs in libbpf.h pair their arrays with a
> cnt field: bpf_kprobe_multi_opts uses cnt, bpf_uprobe_multi_opts uses
> cnt, and bpf_tracing_multi_opts uses cnt. This looks like the only nr_*
> field in the public header, and the field name becomes part of the stable
> public API once it ships.
> 

I agree that a cnt-style name is more consistent here. I won't use
`btf_module_cnt`, though, as it could be confused with
`obj->btf_module_cnt`. I'll use `btf_module_names_cnt` instead to keep
the distinction clear.

>>
>>  	size_t :0;
>>  };
>> -#define bpf_object_open_opts__last_field bpf_token_path
>> +#define bpf_object_open_opts__last_field nr_btf_module_names
> 
> 
> ---
> AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
> See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
> 
> CI run summary: https://github.com/kernel-patches/bpf/actions/runs/33399468751