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From: Jiri Olsa <olsajiri@gmail.com>
To: Alan Maguire <alan.maguire@oracle.com>
Cc: Jiri Olsa <olsajiri@gmail.com>,
	Yonghong Song <yonghong.song@linux.dev>,
	Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
	dwarves@vger.kernel.org, Alexei Starovoitov <ast@kernel.org>,
	Andrii Nakryiko <andrii@kernel.org>,
	bpf@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH dwarves v7 0/5] pahole: Encode true signatures in kernel BTF
Date: Wed, 24 Jun 2026 11:28:04 +0200	[thread overview]
Message-ID: <ajujJM9N0_QpB_3d@krava> (raw)
In-Reply-To: <b1b73cef-f25a-443d-8557-4cfe92938b46@oracle.com>

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

  parent reply	other threads:[~2026-06-24  9:28 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-06-23  4:07 [PATCH dwarves v7 0/5] pahole: Encode true signatures in kernel BTF Yonghong Song
2026-06-23  4:07 ` [PATCH dwarves v7 1/5] dwarf_loader: Detect aggregate ABI register usage and signature changes Yonghong Song
2026-06-23  4:07 ` [PATCH dwarves v7 2/5] dwarf_loader: Collect per-parameter information Yonghong Song
2026-06-23  4:07 ` [PATCH dwarves v7 3/5] dwarf_loader: Analyze per-parameter information for true signatures Yonghong Song
2026-06-23  4:07 ` [PATCH dwarves v7 4/5] btf_encoder: Emit true function signatures Yonghong Song
2026-06-23  4:07 ` [PATCH dwarves v7 5/5] tests: Add BTF true_signature encoding tests Yonghong Song
2026-06-23 12:28 ` [PATCH dwarves v7 0/5] pahole: Encode true signatures in kernel BTF Jiri Olsa
2026-06-23 13:11   ` Alan Maguire
2026-06-23 16:02     ` Alan Maguire
2026-06-23 16:49       ` Yonghong Song
2026-06-23 16:58       ` Yonghong Song
2026-06-24  9:28       ` Jiri Olsa [this message]
2026-06-24 13:52         ` Yonghong Song

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