[PATCH] x86: add -freg-struct-return to CFLAGS

Jeremy Fitzhardinge suggested the use of -freg-struct-return, which does
structure-returns (such as when using pte_t) in registers instead of on
the stack.

that is indeed so, and this option reduced the kernel size a bit:

    text    data     bss     dec     hex filename
 4799506  543456 3760128 9103090  8ae6f2 vmlinux.before
 4798117  543456 3760128 9101701  8ae185 vmlinux.after

the resulting kernel booted fine on my testbox. Lets go for it.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/i386/Makefile b/arch/i386/Makefile
index f7ac1ae..bd28f9f 100644 (file)
--- a/arch/i386/Makefile
+++ b/arch/i386/Makefile
@@ -31,7 +31,7 @@ LDFLAGS_vmlinux := --emit-relocs
 endif
 CHECKFLAGS     += -D__i386__
 
-CFLAGS += -pipe -msoft-float -mregparm=3
+CFLAGS += -pipe -msoft-float -mregparm=3 -freg-struct-return
 
 # prevent gcc from keeping the stack 16 byte aligned
 CFLAGS += $(call cc-option,-mpreferred-stack-boundary=2)