Re: [PATCH bpf-next] libbpf: fix -Wformat warnings from format/argument type mismatches

[Quentin Monnet <qmo@kernel.org>]

2026-06-30 13:15 UTC-0700 ~ Andrii Nakryiko <andrii.nakryiko@gmail.com>
> On Tue, Jun 30, 2026 at 1:01 PM Quentin Monnet <qmo@kernel.org> wrote:
>>
>> 2026-06-30 11:32 UTC-0700 ~ Andrii Nakryiko <andrii.nakryiko@gmail.com>
>>> On Fri, Jun 26, 2026 at 6:30 AM <patchwork-bot+netdevbpf@kernel.org> wrote:
>>>>
>>>> Hello:
>>>>
>>>> This patch was applied to bpf/bpf-next.git (master)
>>>> by Alexei Starovoitov <ast@kernel.org>:
>>>>
>>>> On Wed, 24 Jun 2026 13:49:46 -0700 you wrote:
>>>>> Building libbpf with -Wall (as happens via bpftool's bootstrap build)
>>>>> surfaces ~120 -Wformat warnings where pr_warn/pr_debug format specifiers
>>>>> don't match their argument types: %d for __u32/Elf64_Word, %u for signed
>>>>> ints, %zd for size_t, %ld for unsigned long, and %x/%lx/%llx applied to
>>>>> signed values.
>>>>>
>>>>> Match each specifier to its argument's type where a correctly-signed
>>>>> specifier exists (%d<->%u, %ld->%lu, %zd->%zu). For hex conversions,
>>>>> which have no signed form, cast the argument instead (%x->(unsigned),
>>>>> %lx->(unsigned long), %llx->(unsigned long long)). No functional change.
>>>>>
>>>>> [...]
>>>>
>>>> Here is the summary with links:
>>>>   - [bpf-next] libbpf: fix -Wformat warnings from format/argument type mismatches
>>>>     https://git.kernel.org/bpf/bpf-next/c/df3153758ddb
>>>>
>>>
>>> Quentin,
>>>
>>> I synced these changes to libbpf's Github mirror. Can you please
>>> update bpftool mirror's libbpf reference to include this change, so
>>> that I can fix these noisy warnings for wprof? Thanks!
>>
>>
>> Hi Andrii, I just synced it, thank you.
>>
> 
> Thanks, Quentin!
> 
> I got a bunch of new ones with latest bpftool sync, I haven't looked
> into it, but thought I'll mention in case it's something on bpftool's
> Github Makefile side:

[...]

Oh, I haven't observed these on my setup, I'll try to look into it when
I can. What compiler do you use? And do you see the same when compiling
from the kernel repo? The Makefiles should be rather close, in theory.

Quentin