Re: [PATCH dwarves v7 0/5] pahole: Encode true signatures in kernel BTF

[Yonghong Song <yonghong.song@linux.dev>]

On 6/24/26 2:28 AM, Jiri Olsa wrote:
> On Tue, Jun 23, 2026 at 05:02:30PM +0100, Alan Maguire wrote:
>
> SNIP
>
>>>> hi,
>>>> I tried to get the numbers from my setup and noticed that some new
>>>> functions were included in BTF compared to the current version
>>>> (functions diff attached below)
>>>>
>>>> like for "arp_process" function the current pahole gives me:
>>>>
>>>>    arp_process : skipping BTF encoding of function due to unexpected register usage for parameter
>>>>
>>>> but it's included in BTF generated with the new pahole.
>>>>
>>>> in addition to your explanation above also one of the commit says:
>>>>
>>>>       - a parameter with no location, a constant value, or (for non-clang) no
>>>>         register found is marked optimized out
>>>>
>>>> please check below, it seems like 2nd argument of arp_process has no location,
>>>> so iiuc it should not be included in BTF, right?
>>>>
>>>> thanks,
>>>> jirka
>>>>
>>>>
>>> thanks for catching this; it looks like we return a bit early before detecting
>>> missing locations in the non-true-signature code. If you get a chance, would you
>>> mind trying the attached patch to see if it fixes the problem?
>>>
>>> If the fix works and Yonghong is happy with it we can add it as a followup
>>> and land the true signature series to save another round.
>> actually sorry that patch leaked true signature partial names for gcc; updated
>> patch attached.
> hum, I can't apply either of them, but I see that change on top of:
>    alan-maguire/dwarves-true-sig-v7
>
> but on that branch I can still see arp_process function in the btf
>
> please let me know if I should try some other branch

Jiri,

Please take a look at v9: https://lore.kernel.org/bpf/20260624052553.3139112-1-yonghong.song@linux.dev/

It has version 7 plus Alan's changes in version 7 comments. I forther added a
few changes related to llvm and another patch to resolve some inconsistency.

Thanks!

Yonghong

>
> thanks,
> jirka