Re: [PATCH 3.12 55/64] x86: vvar, fix excessive gcc-6 DECLARE_VVAR warnings

From	Andy Lutomirski <luto@amacapital.net>
Newsgroups	linux.kernel
Subject	Re: [PATCH 3.12 55/64] x86: vvar, fix excessive gcc-6 DECLARE_VVAR warnings
Date	2016-02-12 17:50 +0100
Message-ID	<r1p4R-14o-7@gated-at.bofh.it> (permalink)
References	<r0ZWO-17m-3@gated-at.bofh.it> <r0ZWP-17m-23@gated-at.bofh.it> <r106w-1qh-57@gated-at.bofh.it>
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On Thu, Feb 11, 2016 at 5:59 AM, Jiri Slaby <jslaby@suse.cz> wrote:
> 3.12-stable review patch.  If anyone has any objections, please let me know.
>
> ===============
>
> On 3.12, with gcc-6, I see a lot of:
> arch/x86/include/asm/vvar.h:33:28: warning: ‘vvaraddr_jiffies’ defined but not used [-Wunused-const-variable]
>   static type const * const vvaraddr_ ## name =   \
>                             ^
> arch/x86/include/asm/vvar.h:46:1: note: in expansion of macro ‘DECLARE_VVAR’
>  DECLARE_VVAR(0, volatile unsigned long, jiffies)
>  ^~~~~~~~~~~~
>
> In upstream, this is fixed by ef721987ae (x86, vdso: Introduce VVAR
> marco for vdso32) and f40c330091 (x86, vdso: Move the vvar and hpet
> mappings next to the 64-bit vDSO). But this is not applicable to
> stable.
>
> So mark the vvar declaration as __maybe_unused and be done with it.
> This will generate it to the code only if it is used. I.e. the same as
> with gcc < 6.

LGTM.

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[PATCH 3.12 55/64] x86: vvar, fix excessive gcc-6 DECLARE_VVAR warnings Jiri Slaby <jslaby@suse.cz> - 2016-02-11 15:10 +0100
  Re: [PATCH 3.12 55/64] x86: vvar, fix excessive gcc-6 DECLARE_VVAR warnings Andy Lutomirski <luto@amacapital.net> - 2016-02-12 17:50 +0100

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