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Subject[PATCH] [31/35] i386: Fix usage of -mtune when X86_GENERIC=y or CONFIG_MCORE2=y
Date

From: Lasse Collin <lasse.collin@tukaani.org>
Hi!

I sent this simple patch to lkml about two weeks ago and also cc'ed
to Linus, but seems that the patch got ignored. I decided to write to
you, because you have modified the relevant file most recently.

Below is a copy of the mail that is also available at
<http://lkml.org/lkml/2007/2/28/230>.

Signed-off-by: Andi Kleen <ak@suse.de>

---
Two fixes to arch/i386/Makefile.cpu:

1) When X86_GENERIC=y is set, use -mtune=i686 if $(CC) doesn't
support -mtune=generic. GCC 4.1.2 and earlier don't support
-mtune=generic. When building a generic kernel for a distro
that runs on i586 and better, it is nice to use
-march=i586 -mtune=i686 instead of plain -march=i586.

2) Use $(call tune) instead of hardcoded -mtune when CONFIG_MCORE2=y.
This makes it possible to have CONFIG_MCORE2=y when using GCC 3.3,
which uses -mcpu instead of -mtune. Also dropped fallback to
-mtune=generic and -mtune=i686, because -march=i686 already
implies -mtune=i686.

The patch is against 2.6.20, but Makefile.cpu hasn't changed recently.

---
arch/i386/Makefile.cpu | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
Index: linux/arch/i386/Makefile.cpu
===================================================================
--- linux.orig/arch/i386/Makefile.cpu
+++ linux/arch/i386/Makefile.cpu
@@ -4,9 +4,9 @@
#-mtune exists since gcc 3.4
HAS_MTUNE := $(call cc-option-yn, -mtune=i386)
ifeq ($(HAS_MTUNE),y)
-tune = $(call cc-option,-mtune=$(1),)
+tune = $(call cc-option,-mtune=$(1),$(2))
else
-tune = $(call cc-option,-mcpu=$(1),)
+tune = $(call cc-option,-mcpu=$(1),$(2))
endif

align := $(cc-option-align)
@@ -33,7 +33,7 @@ cflags-$(CONFIG_MWINCHIP3D) += $(call cc
cflags-$(CONFIG_MCYRIXIII) += $(call cc-option,-march=c3,-march=i486) $(align)-functions=0 $(align)-jumps=0 $(align)-loops=0
cflags-$(CONFIG_MVIAC3_2) += $(call cc-option,-march=c3-2,-march=i686)
cflags-$(CONFIG_MVIAC7) += -march=i686
-cflags-$(CONFIG_MCORE2) += -march=i686 $(call cc-option,-mtune=core2,$(call cc-option,-mtune=generic,-mtune=i686))
+cflags-$(CONFIG_MCORE2) += -march=i686 $(call tune,core2)

# AMD Elan support
cflags-$(CONFIG_X86_ELAN) += -march=i486
@@ -43,5 +43,5 @@ cflags-$(CONFIG_MGEODEGX1) += -march=pen

# add at the end to overwrite eventual tuning options from earlier
# cpu entries
-cflags-$(CONFIG_X86_GENERIC) += $(call tune,generic)
+cflags-$(CONFIG_X86_GENERIC) += $(call tune,generic,$(call tune,i686))

-
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