[PATCH 2/2] powerpc: Fix defconfig choice logic when cross compiling

[Mathieu Malaterre]

On Thu, Feb 7, 2019 at 6:20 AM Michael Ellerman <mpe at ellerman.id.au> wrote:
>
> Our logic for choosing defconfig doesn't work well in some situations.
>
> For example if you're on a ppc64le machine but you specify a non-empty
> CROSS_COMPILE, in order to use a non-default toolchain, then defconfig
> will give you ppc64_defconfig (big endian):
>
>   $ make CROSS_COMPILE=~/toolchains/gcc-8/bin/powerpc-linux- defconfig
>   *** Default configuration is based on 'ppc64_defconfig'
>
> This is because we assume that CROSS_COMPILE being set means we
> can't be on a ppc machine and rather than checking we just default to
> ppc64_defconfig.
>
> We should just ignore CROSS_COMPILE, instead check the machine with
> uname and if it's one of ppc, ppc64 or ppc64le then use that
> defconfig. If it's none of those then we fall back to ppc64_defconfig.

How about shamelessly copying x86:

diff --git a/Makefile b/Makefile
index 3142e67d03f1..041616742142 100644
--- a/Makefile
+++ b/Makefile
@@ -351,6 +351,14 @@ ifeq ($(ARCH),sparc64)
        SRCARCH := sparc
 endif

+# Additional ARCH settings for ppc
+ifeq ($(ARCH),ppc64)
+       SRCARCH := powerpc
+endif
+ifeq ($(ARCH),ppc64el)
+       SRCARCH := powerpc
+endif
+
 # Additional ARCH settings for sh
 ifeq ($(ARCH),sh64)
        SRCARCH := sh
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 10bf5dc7cdf0..cbb679fb7162 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -34,10 +34,17 @@ ifdef CONFIG_PPC_BOOK3S_32
 KBUILD_CFLAGS          += -mcpu=powerpc
 endif

-# If we're on a ppc/ppc64/ppc64le machine use that defconfig,
otherwise just use
-# ppc64_defconfig because we have nothing better to go on.
-uname := $(shell uname -m)
-KBUILD_DEFCONFIG := $(if $(filter ppc%,$(uname)),$(uname),ppc64)_defconfig
+# select defconfig based on actual architecture
+ifeq ($(ARCH),powerpc)
+  ifeq ($(shell uname -m),ppc64)
+        KBUILD_DEFCONFIG := ppc64_defconfig
+  else
+        KBUILD_DEFCONFIG := ppc_defconfig
+  endif
+else
+        KBUILD_DEFCONFIG := $(ARCH)_defconfig
+endif
+

 ifdef CONFIG_PPC64
 new_nm := $(shell if $(NM) --help 2>&1 | grep -- '--synthetic' >
/dev/null; then echo y; else echo n; fi)


> Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
> ---
>  arch/powerpc/Makefile | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
> index 70e6e8119aeb..81563986a30e 100644
> --- a/arch/powerpc/Makefile
> +++ b/arch/powerpc/Makefile
> @@ -34,11 +34,10 @@ ifdef CONFIG_PPC_BOOK3S_32
>  KBUILD_CFLAGS          += -mcpu=powerpc
>  endif
>
> -ifeq ($(CROSS_COMPILE),)
> -KBUILD_DEFCONFIG := $(shell uname -m)_defconfig
> -else
> -KBUILD_DEFCONFIG := ppc64_defconfig
> -endif
> +# If we're on a ppc/ppc64/ppc64le machine use that defconfig, otherwise just use
> +# ppc64_defconfig because we have nothing better to go on.
> +uname := $(shell uname -m)
> +KBUILD_DEFCONFIG := $(if $(filter ppc%,$(uname)),$(uname),ppc64)_defconfig
>
>  ifdef CONFIG_PPC64
>  new_nm := $(shell if $(NM) --help 2>&1 | grep -- '--synthetic' > /dev/null; then echo y; else echo n; fi)
> --
> 2.20.1
>