[PATCH] powerpc/kbuild: set generic machine type for compile with 64-bit toolchain

[PATCH] powerpc/kbuild: set generic machine type for compile with 64-bit toolchain

[Nicholas Piggin]

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 | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 95813df90801..aa6464c81a9f 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -24,6 +24,12 @@ ifeq ($(HAS_BIARCH),y)
 ifeq ($(CROSS32_COMPILE),)
 CROSS32CC	:= $(CC) -m32
 KBUILD_ARFLAGS	+= --target=elf32-powerpc
+
+# 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
 endif
 
-- 
2.17.0

Re: [PATCH] powerpc/kbuild: set generic machine type for compile with 64-bit toolchain

[Nicholas Piggin]

Bad title, should be set generic machine type for 32-bit compile with
64-bit toolchain

On Thu, 10 May 2018 10:26:37 +1000
Nicholas Piggin <npiggin@gmail.com> wrote:

> 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 | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
> index 95813df90801..aa6464c81a9f 100644
> --- a/arch/powerpc/Makefile
> +++ b/arch/powerpc/Makefile
> @@ -24,6 +24,12 @@ ifeq ($(HAS_BIARCH),y)
>  ifeq ($(CROSS32_COMPILE),)
>  CROSS32CC	:= $(CC) -m32
>  KBUILD_ARFLAGS	+= --target=elf32-powerpc
> +
> +# 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
>  endif
>  

Re: [PATCH] powerpc/kbuild: set generic machine type for compile with 64-bit toolchain

[Nicholas Piggin]

On Thu, 10 May 2018 10:26:37 +1000
Nicholas Piggin <npiggin@gmail.com> wrote:

> 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.

Actually ignore this patch, it had a few other problems. I'll send a new
version out.

Thanks,
Nick