linux-kernel - [PATCH] x86: set fpmath to 387 to avoid gcc warnings

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Date:	Wed,  8 Aug 2012 09:27:41 +0300
From:	Dragos Tatulea <dragos.tatulea@...el.com>
To:	hpa@...ux.intel.com
Cc:	linux-kernel@...r.kernel.org,
	Dragos Tatulea <dragos.tatulea@...el.com>
Subject: [PATCH] x86: set fpmath to 387 to avoid gcc warnings

If gcc has a different default fpmath set (ex: sse),
many unuseful warnings will be spewed.

This can affect out of tree modules that compile with
-Werror (ex: systemtap stp scripts).

Be paranoid and add -msoft-float as well to try to
get an error if FP instructions are generated at all.

Signed-off-by: Dragos Tatulea <dragos.tatulea@...el.com>
---
 arch/x86/Makefile |    1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index b1c611e..b771d0b 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -130,6 +130,7 @@ KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
 # prevent gcc from generating any FP code by mistake
 KBUILD_CFLAGS += $(call cc-option,-mno-sse -mno-mmx -mno-sse2 -mno-3dnow,)
 KBUILD_CFLAGS += $(call cc-option,-mno-avx,)
+KBUILD_CFLAGS += $(call cc-option,-mfpmath=387 -msoft-float,)
 
 KBUILD_CFLAGS += $(mflags-y)
 KBUILD_AFLAGS += $(mflags-y)
-- 
1.7.9.5

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