linux-kernel - Re: [PATCH v2] x86/boot/KASLR: Fix unused variable warning

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Message-ID: <20200109184055.GI5603@zn.tnic>
Date:   Thu, 9 Jan 2020 19:40:55 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Zhenzhong Duan <zhenzhong.duan@...il.com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...e.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Chao Fan <fanc.fnst@...fujitsu.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: Re: [PATCH v2] x86/boot/KASLR: Fix unused variable warning

On Fri, Jan 03, 2020 at 11:39:29AM +0800, Zhenzhong Duan wrote:
> Local variable 'i' is referenced only when CONFIG_MEMORY_HOTREMOVE and
> CONFIG_ACPI are defined, but definition of variable 'i' is out of guard.
> If any of the two macros is undefined, below warning triggers during
> build, fix it by moving 'i' in the guard.
> 
> arch/x86/boot/compressed/kaslr.c:698:6: warning: unused variable ‘i’ [-Wunused-variable]

How do you trigger this?

I have:

$  grep -E "(CONFIG_MEMORY_HOTREMOVE|CONFIG_ACPI)" .config
# CONFIG_ACPI is not set

but no warning. Neither with gcc 8 nor with gcc 9.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette