From: Venkat <redacted>
Date: Mon, 13 Oct 2025 09:27:14 +0530

quoted

On 12 Sep 2025, at 7:00 PM, Alexander Lobakin [off-list ref] wrote:

From: Venkat Rao Bagalkote <redacted>
Date: Fri, 12 Sep 2025 18:39:33 +0530

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Greetings!!!


IBM CI has reported a build warning on IBM Power Server, on linux-
next20250912 kernel.


gcc version 11.5.0 20240719 (Red Hat 11.5.0-2) (GCC)

GNU ld version 2.35.2-54.el9


Attached is the .config file.


Warnings:

In file included from drivers/net/ethernet/intel/idpf/xdp.c:6:
drivers/net/ethernet/intel/idpf/xdp.h: In function ‘idpf_xdp_tx_xmit’:
drivers/net/ethernet/intel/idpf/xdp.h:28:20: note: the ABI of passing
aggregates with 16-byte alignment has changed in GCC 5

BTW wait, "note"? It's not even a warning?

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  28 | static inline void idpf_xdp_tx_xmit(struct libeth_xdp_tx_desc
desc, u32 i,
     |                    ^~~~~~~~~~~~~~~~

Yes, I do pass 16-byte variables/structures directly.

I would say this warning makes no sense, due to the following reasons:

1. IIRC the minimum required GCC version for building the latest kernel
  is way above 5.
2. This warning should appear only with `-Wabi`, which the upstream
  kernel never sets.

Now, this warning is seen on upstream kernel also. 

Then how to reproduce it? I've never seen a single report from the
upstream CI bots which would point out to such warning.

Could RH enable some additional output by default in their GCC?

Not sure if this is something we need to fix it or suppress the warning?

There's nothing to fix nor suppress.

Regards,
Venkat.

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3. Kernel is a self-contained project, this function is not uAPI, so we
  shouldn't care in general about backward ABI compatibility for purely
  in-kernel stuff.

We have plenty of functions, mostly generic, which either passes or
returns >= 16-byte objects, but I see this warning for the first time.
Despite that my repo is attached to the open Intel CI bots infra which
does daily builds on a good bunch of different architectures and
toolchains (inc. GCC 8+).

Thanks,
Olek