Date: Mon, 4 Jun 2012 10:36:43 -0400
From: Don Zickus <dzickus@redhat.com>
To: Witold Baryluk <baryluk@smp.if.uj.edu.pl>
Cc: linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
        x86@kernel.org
Subject: Re: WARNING: arch/x86/built-in.o: Section mismatch in reference from
 the variable test_nmi_ipi_callback_na to function
 .ini.text:test_nmi_ipi_callback
Message-ID: <20120604143643.GJ32472@redhat.com>
References: <20120602161502.GW16584@smp.if.uj.edu.pl>
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On Sat, Jun 02, 2012 at 06:15:02PM +0200, Witold Baryluk wrote:
> Hello everybody,
> 
> x86 32-bit Build just got 2 WARNINGS when building kernel on Linus' tree.

Hi Witold,

Thanks for the warnings.

> 
> 
>  VDSOSYM arch/x86/vdso/vdso32-syms.lds
>   LD      arch/x86/vdso/built-in.o
>   LD      arch/x86/built-in.o
> WARNING: arch/x86/built-in.o(.data+0x5af0): Section mismatch in reference from the variable test_nmi_ipi_callback_na.10451 to the function .init.text:test_nmi_ipi_callback()
> The variable test_nmi_ipi_callback_na.10451 references
> the function __init test_nmi_ipi_callback()
> If the reference is valid then annotate the
> variable with __init* or __refdata (see linux/init.h) or name the variable:
> *_template, *_timer, *_sht, *_ops, *_probe, *_probe_one, *_console
> 
> WARNING: arch/x86/built-in.o(.data+0x5b04): Section mismatch in reference from the variable nmi_unk_cb_na.10399 to the function .init.text:nmi_unk_cb()
> The variable nmi_unk_cb_na.10399 references
> the function __init nmi_unk_cb()
> If the reference is valid then annotate the
> variable with __init* or __refdata (see linux/init.h) or name the variable:
> *_template, *_timer, *_sht, *_ops, *_probe, *_probe_one, *_console

These are intermediate variables test_nmi_ipi_callback_na.10451 and
nmi_unk_cb_na.10399.  I do not know how to fix them.

Basically the test registers two nmi_handlers, run some tests, and
then unregisters them.  Those handlers are what the compiler seems to be
complaining about.  I do not know what magic to pass the compiler to let
it know that both of the handlers will be unregistered before the init
section is destroyed.

Perhaps I should tag those callbacks with __ref? I am not sure the right
thing to do here.

Cheers,
Don

> 
>   LD      vmlinux.o
>   MODPOST vmlinux.o
> WARNING: vmlinux.o(.data+0x7cf0): Section mismatch in reference from the variable test_nmi_ipi_callback_na.10451 to the function .init.text:test_nmi_ipi_callback()
> The variable test_nmi_ipi_callback_na.10451 references
> the function __init test_nmi_ipi_callback()
> If the reference is valid then annotate the
> variable with __init* or __refdata (see linux/init.h) or name the variable:
> *_template, *_timer, *_sht, *_ops, *_probe, *_probe_one, *_console
> 
> WARNING: vmlinux.o(.data+0x7d04): Section mismatch in reference from the variable nmi_unk_cb_na.10399 to the function .init.text:nmi_unk_cb()
> The variable nmi_unk_cb_na.10399 references
> the function __init nmi_unk_cb()
> If the reference is valid then annotate the
> variable with __init* or __refdata (see linux/init.h) or name the variable:
> *_template, *_timer, *_sht, *_ops, *_probe, *_probe_one, *_console
> 
>   GEN     .version
>   CHK     include/generated/compile.h
> 
> 
> 
> 
> This is recent change.
> 
> gcc version 4.7.0 (Debian 4.7.0-11) 
> 
> Debian sid, i386.
> 
> -- 
> Witold Baryluk
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