From: Arvind Sankar <nivedita@alum.mit.edu>
To: Borislav Petkov <bp@alien8.de>
Cc: Zhenzhong Duan <zhenzhong.duan@gmail.com>,
linux-kernel@vger.kernel.org, x86@kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@suse.de>,
"H. Peter Anvin" <hpa@zytor.com>,
Chao Fan <fanc.fnst@cn.fujitsu.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Subject: Re: [PATCH v2] x86/boot/KASLR: Fix unused variable warning
Date: Thu, 9 Jan 2020 15:46:41 -0500 [thread overview]
Message-ID: <20200109204638.GA523773@rani.riverdale.lan> (raw)
In-Reply-To: <20200109184055.GI5603@zn.tnic>
On Thu, Jan 09, 2020 at 07:40:55PM +0100, Borislav Petkov wrote:
> 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
The boot/compressed Makefile resets KBUILD_CFLAGS. Following hack and
building with W=1 shows it, or just add -Wunused in there.
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 56aa5fa0a66b..791c0d5a952a 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -35,6 +35,9 @@ KBUILD_CFLAGS += $(cflags-y)
KBUILD_CFLAGS += -mno-mmx -mno-sse
KBUILD_CFLAGS += $(call cc-option,-ffreestanding)
KBUILD_CFLAGS += $(call cc-option,-fno-stack-protector)
+
+include scripts/Makefile.extrawarn
+
KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)
KBUILD_CFLAGS += $(call cc-disable-warning, gnu)
KBUILD_CFLAGS += -Wno-pointer-sign
next prev parent reply other threads:[~2020-01-09 20:46 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-03 3:39 [PATCH v2] x86/boot/KASLR: Fix unused variable warning Zhenzhong Duan
2020-01-09 18:40 ` Borislav Petkov
2020-01-09 20:46 ` Arvind Sankar [this message]
2020-01-09 20:50 ` Borislav Petkov
2020-01-10 2:09 ` Zhenzhong Duan
2020-01-10 8:27 ` Borislav Petkov
2020-01-10 8:36 ` Zhenzhong Duan
2020-01-10 9:01 ` Borislav Petkov
2020-01-10 2:27 ` Zhenzhong Duan
2020-01-10 9:00 ` Borislav Petkov
2020-01-13 2:43 ` Zhenzhong Duan
2020-01-24 11:09 ` Borislav Petkov
2020-01-09 21:00 ` Thomas Gleixner
2020-01-10 8:46 ` Zhenzhong Duan
2020-01-10 13:13 ` Thomas Gleixner
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