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

Jiri Olsa <[email protected]> Wed, 24 Jun 2026 11:28:04 +0200
Newsgroups org.kernel.vger.dwarves,org.kernel.vger.bpf
Message-ID <ajujJM9N0_QpB_3d@krava>
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

thanks,
jirka