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

Nicholas Piggin
2018-05-10T05:17:14Z

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 <npiggin@gmail.com>
---
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