powerpc: Add ability to build little endian kernels
This patch allows the kbuild system to successfully compile a kernel
for the little endian PowerPC64 architecture. A subsequent patch
will add the CONFIG_CPU_LITTLE_ENDIAN kernel config option which
must be set to build such a kernel.
If cross compiling, CROSS_COMPILE must point to a suitable toolchain
(compiled for the powerpc64le-linux and powerpcle-linux targets).
Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index debfa2b..d3c91bf 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -65,11 +65,29 @@
UTS_MACHINE := $(OLDARCH)
+ifeq ($(CONFIG_CPU_LITTLE_ENDIAN),y)
+override CC += -mlittle-endian
+override AS += -mlittle-endian
+override LD += -EL
+override CROSS32CC += -mlittle-endian
+override CROSS32AS += -mlittle-endian
+LDEMULATION := lppc
+GNUTARGET := powerpcle
+MULTIPLEWORD := -mno-multiple
+else
+override CC += -mbig-endian
+override AS += -mbig-endian
+override LD += -EB
+LDEMULATION := ppc
+GNUTARGET := powerpc
+MULTIPLEWORD := -mmultiple
+endif
+
ifeq ($(HAS_BIARCH),y)
override AS += -a$(CONFIG_WORD_SIZE)
-override LD += -m elf$(CONFIG_WORD_SIZE)ppc
+override LD += -m elf$(CONFIG_WORD_SIZE)$(LDEMULATION)
override CC += -m$(CONFIG_WORD_SIZE)
-override AR := GNUTARGET=elf$(CONFIG_WORD_SIZE)-powerpc $(AR)
+override AR := GNUTARGET=elf$(CONFIG_WORD_SIZE)-$(GNUTARGET) $(AR)
endif
LDFLAGS_vmlinux-y := -Bstatic
@@ -95,7 +113,7 @@
CFLAGS-$(CONFIG_PPC64) := -mtraceback=no -mcall-aixdesc
CFLAGS-$(CONFIG_PPC64) += $(call cc-option,-mcmodel=medium,-mminimal-toc)
CFLAGS-$(CONFIG_PPC64) += $(call cc-option,-mno-pointers-to-nested-functions)
-CFLAGS-$(CONFIG_PPC32) := -ffixed-r2 -mmultiple
+CFLAGS-$(CONFIG_PPC32) := -ffixed-r2 $(MULTIPLEWORD)
ifeq ($(CONFIG_PPC_BOOK3S_64),y)
CFLAGS-$(CONFIG_GENERIC_CPU) += $(call cc-option,-mtune=power7,-mtune=power4)