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From:   Michael Ellerman <mpe@ellerman.id.au>
To:     John Ogness <john.ogness@linutronix.de>,
        Nicholas Piggin <npiggin@gmail.com>
Cc:     linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] powerpc/build: vdso linker warning for orphan sections
In-Reply-To: <87o7k9l2oj.fsf@jogness.linutronix.de>
References: <20230609051002.3342-1-npiggin@gmail.com>
 <871qh6wcgb.fsf@jogness.linutronix.de> <871qh5jrz2.fsf@mail.lhotse>
 <87o7k9l2oj.fsf@jogness.linutronix.de>
Date:   Wed, 19 Jul 2023 21:55:34 +1000
Message-ID: <87ttu0i095.fsf@mail.lhotse>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

John Ogness <john.ogness@linutronix.de> writes:
> On 2023-07-18, Michael Ellerman <mpe@ellerman.id.au> wrote:
>>> ld: warning: discarding dynamic section .rela.opd
>>>
>>> and bisects to:
>>>
>>> 8ad57add77d3 ("powerpc/build: vdso linker warning for orphan sections")
>>
>> Can you test with a newer compiler/binutils?
>
> Testing the Debian release cross compilers/binutils:
>
> Debian 10 / gcc 8.3.0  / ld 2.31.1: generates the warning
>
> Debian 11 / gcc 10.2.1 / ld 2.35.2: generates the warning
>
> Debian 12 / gcc 12.2.0 / ld 2.40:   does _not_ generate the warning
>
> I suppose moving to the newer toolchain is the workaround. Although it
> is a bit unusual to require such a modern toolchain in order to build a
> kernel without warnings.

I didn't mean that you should move to a new toolchain to avoid the
warning, I was just curious why you're the only person to see it.

I regularly test with a gcc 5.5.0 / ld 2.29 toolchain and gcc 13.1.1 /
ld 2.39, and I haven't seen the warning. I tried a bunch of others and
can't reproduce it.

Can you confirm that this makes the warning go away?

cheers


diff --git a/arch/powerpc/kernel/vdso/vdso64.lds.S b/arch/powerpc/kernel/vdso/vdso64.lds.S
index bda6c8cdd459..286e1597c548 100644
--- a/arch/powerpc/kernel/vdso/vdso64.lds.S
+++ b/arch/powerpc/kernel/vdso/vdso64.lds.S
@@ -85,7 +85,7 @@ SECTIONS
 		*(.branch_lt)
 		*(.data .data.* .gnu.linkonce.d.* .sdata*)
 		*(.bss .sbss .dynbss .dynsbss)
-		*(.opd)
+		*(.opd .rela.opd)
 		*(.glink .iplt .plt .rela*)
 	}
 }