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

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

[dragos.tatulea]

From: Dragos Tatulea <dragos.tatulea@intel.com>

If gcc has a different default fpmath set (e.g. sse),
many unuseful warnings will be spewed when compiling on an
architecture that doesn't support it.

An example would be Google's Android 4.1 x86 toochain which
is compiled with -mfpmath=sse.

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

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

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index b1c611e..f4fefb8 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,)
 
 KBUILD_CFLAGS += $(mflags-y)
 KBUILD_AFLAGS += $(mflags-y)
-- 
1.7.9.5

Re: [PATCH] x86: set fpmath to 387 to avoid gcc warnings

[H. Peter Anvin]

On 08/06/2012 04:36 AM, dragos.tatulea@intel.com wrote:
> From: Dragos Tatulea <dragos.tatulea@intel.com>
> 
> If gcc has a different default fpmath set (e.g. sse),
> many unuseful warnings will be spewed when compiling on an
> architecture that doesn't support it.
> 
> An example would be Google's Android 4.1 x86 toochain which
> is compiled with -mfpmath=sse.
> 
> This can affect out of tree modules that compile with
> -Werror (ex: systemtap stp scripts).
> 
> Signed-off-by: Dragos Tatulea <dragos.tatulea@intel.com>
> ---
>  arch/x86/Makefile |    1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/x86/Makefile b/arch/x86/Makefile
> index b1c611e..f4fefb8 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,)
>  
>  KBUILD_CFLAGS += $(mflags-y)
>  KBUILD_AFLAGS += $(mflags-y)
> 

I guess we should do -msoft-float as well to try to get an error if FP
instructions are generated at all...

	-hpa

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

[Dragos Tatulea]

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.

Change-Id: If9271d7aea7371f394ede0bc5e3ed1383cdb0e1a
Signed-off-by: Dragos Tatulea <dragos.tatulea@intel.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

Re: [PATCH] x86: set fpmath to 387 to avoid gcc warnings

[Tatulea, Dragos]

On Wed, Aug 8, 2012 at 9:27 AM, Dragos Tatulea <dragos.tatulea@intel.com> wrote:
> 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.
>
> Change-Id: If9271d7aea7371f394ede0bc5e3ed1383cdb0e1a
Ooops, leaked some trash. Patch re-sent.

Thanks,
Dragos

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

[Dragos Tatulea]

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@intel.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