[2.6 patch] Use -ffreestanding?

[Adrian Bunk <bunk@stusta.de>]

On Tue, Nov 09, 2004 at 06:01:07AM +0100, Andi Kleen wrote:
> > Why doesn't the kernel use -ffreestanding which should prevent all such 
> > problems?
> 
> Because we want most of these optimizations. Also with -ffreestanding

Do we really want the compiler to silently replace in-kernel functions 
with built-ins?

You can still do an explicit
  #define strlen __builtin_strlen
if you want to use a gcc built-in function.

> you would need to supply the out of line string functions anyways 
> because gcc wouldn't inline them.

At least with gcc 3.4.2 on i386 adding -ffreestanding and your 
(i386-specific) IN_STRING_C hack removed compiles fine.

> -Andi


I'm open for examples why this actually doesn't work, but after my 
(limited) testin I'd suggest the patch below for inclusion in the next 
-mm.


Signed-off-by: Adrian Bunk <bunk@stusta.de>

--- linux-2.6.10-rc1-mm4-full-ffreestanding/Makefile.old	2004-11-09 22:27:06.000000000 +0100
+++ linux-2.6.10-rc1-mm4-full-ffreestanding/Makefile	2004-11-09 22:27:47.000000000 +0100
@@ -349,7 +349,8 @@
 CPPFLAGS        := -D__KERNEL__ $(LINUXINCLUDE)
 
 CFLAGS 		:= -Wall -Wstrict-prototypes -Wno-trigraphs \
-	  	   -fno-strict-aliasing -fno-common
+	  	   -fno-strict-aliasing -fno-common \
+		   -ffreestanding
 AFLAGS		:= -D__ASSEMBLY__
 
 export	VERSION PATCHLEVEL SUBLEVEL EXTRAVERSION LOCALVERSION KERNELRELEASE \