Re: [PATCH bpf-next v12 06/10] bpftool: Generate skeleton for global percpu data

[Leon Hwang]

On 14/8/26 01:56, Andrii Nakryiko wrote:
> On Thu, Aug 13, 2026 at 8:24 AM Leon Hwang <leon.hwang@xxxxxxxxx> wrote:
[...]
>> @@ -263,13 +269,24 @@ static bool is_mmapable_map(const struct bpf_map *map, char *buf, size_t sz)
>>                 return true;
>>         }
>>
>> -       if (!bpf_map__is_internal(map) || !(bpf_map__map_flags(map) & BPF_F_MMAPABLE))
>> +       if (!bpf_map__is_internal(map))
>>                 return false;
>>
>>         if (!get_map_ident(map, buf, sz))
>>                 return false;
>>
>> -       return true;
>> +       if (bpf_map__map_flags(map) & BPF_F_MMAPABLE)
>> +               return true;
>> +
>> +       if (bpf_map__type(map) == BPF_MAP_TYPE_PERCPU_ARRAY)
>> +               return bpf_map__btf_value_type_id(map) != 0;
> 
> why do we need this btf_value_type_id() check? in what case it's
> expected that there will be no BTF info set?

Add this check by referencing btf_value_type_id check in libbpf's
map_is_mmapable(). That said, if btf_value_type_id is 0 for
global/percpu data, is_mmapable_map() should return false for them.

And, if the bpf obj is compiled without -g, this check helps to avoid
generating struct for percpu data explicitly.

Thanks,
Leon

> 
>> +
>> +       return false;
>> +}
>> +
>> +static bool is_mmapable_map(const struct bpf_map *map, char *buf, size_t sz)
>> +{
>> +       return is_skel_data(map, buf, sz) && bpf_map__type(map) != BPF_MAP_TYPE_PERCPU_ARRAY;
>>  }
>>
> 
> [...]