Subject: [PATCH v2 1/5] powerpc/kbuild: set default generic machine type for 32-bit compile

From: Nicholas Piggin <[email-masked]>
Date: Thu, 10 May 2018 15:16:55 +1000

The 64-bit toolchain uses the wrong ISA variant for compiling 32-bit
kernels, eve with -m32. Set -mcpu=powerpc which is the generic 32-bit
powerpc machine type and scheduling model. 32-bit platforms and CPUs
can override this with -mcpu= options that come later on the command
line.

This fixes a lot of build failures due to incompatible assembly when
compiling 32-bit kernel with 64-bit toolchain.

Signed-off-by: Nicholas Piggin <[email-masked]>
---
 arch/powerpc/Makefile | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 95813df90801..7034b1ad50e0 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -27,6 +27,14 @@ KBUILD_ARFLAGS	+= --target=elf32-powerpc
 endif
 endif
 
+ifdef CONFIG_PPC32
+# These options will be overridden by any -mcpu option that comes
+# later on the command line, but they are needed to set a sane
+# 32-bit cpu target for the 64-bit cross compiler.
+KBUILD_CFLAGS		+= -mcpu=powerpc
+KBUILD_AFLAGS		+= -mcpu=powerpc
+endif
+
 export CROSS32CC CROSS32AR
 
 ifeq ($(CROSS_COMPILE),)
-- 
2.17.0