Re: [PATCH] powerpc/boot: Fix 64-bit boot wrapper build with non-biarch compiler

[Cyril Bur <cyrilbur@gmail.com>]

On Wed, 2017-07-26 at 23:19 +1000, Michael Ellerman wrote:
> Historically the boot wrapper was always built 32-bit big endian, even
> for 64-bit kernels. That was because old firmwares didn't necessarily
> support booting a 64-bit image. Because of that arch/powerpc/boot/Makefile
> uses CROSS32CC for compilation.
> 
> However when we added 64-bit little endian support, we also added
> support for building the boot wrapper 64-bit. However we kept using
> CROSS32CC, because in most cases it is just CC and everything works.
> 
> However if the user doesn't specify CROSS32_COMPILE (which no one ever
> does AFAIK), and CC is *not* biarch (32/64-bit capable), then CROSS32CC
> becomes just "gcc". On native systems that is probably OK, but if we're
> cross building it definitely isn't, leading to eg:
> 
>   gcc ... -m64 -mlittle-endian -mabi=elfv2 ... arch/powerpc/boot/cpm-serial.c
>   gcc: error: unrecognized argument in option ‘-mabi=elfv2’
>   gcc: error: unrecognized command line option ‘-mlittle-endian’
>   make: *** [zImage] Error 2
> 
> To fix it, stop using CROSS32CC, because we may or may not be building
> 32-bit. Instead setup a BOOTCC, which defaults to CC, and only use
> CROSS32_COMPILE if it's set and we're building for 32-bit.
> 
> Fixes: 147c05168fc8 ("powerpc/boot: Add support for 64bit little endian wrapper")
> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Without this patch applied and using a 64bit LE only toolchain my
powernv_defconfig build fails:

gcc: error: unrecognized argument in option ‘-mabi=elfv2’
gcc: note: valid arguments to ‘-mabi=’ are: ms sysv
  BOOTAS  arch/powerpc/boot/crt0.o
  BOOTCC  arch/powerpc/boot/cuboot.o
gcc: error: unrecognized argument in option ‘-mabi=elfv2’
gcc: note: valid arguments to ‘-mabi=’ are: ms sysv
  COPY    arch/powerpc/boot/zlib.h
gcc: error: unrecognized command line option ‘-mlittle-endian’; did you
mean ‘-fconvert=little-endian’?
gcc: error: unrecognized argument in option ‘-mabi=elfv2’
gcc: error: unrecognized command line option ‘-mlittle-endian’; did you
mean ‘-fconvert=little-endian’?
gcc: note: valid arguments to ‘-mabi=’ are: ms sysv
  COPY    arch/powerpc/boot/zutil.h
  COPY    arch/powerpc/boot/inffast.h
  COPY    arch/powerpc/boot/zconf.h
make[1]: *** [arch/powerpc/boot/Makefile:201: arch/powerpc/boot/crt0.o]
Error 1
make[1]: *** Waiting for unfinished jobs....
  MODPOST 244 modules
gcc: error: unrecognized command line option ‘-mlittle-endian’; did you
mean ‘-fconvert=little-endian’?
make[1]: *** [arch/powerpc/boot/Makefile:198: arch/powerpc/boot/cpm-
serial.o] Error 1
make[1]: *** [arch/powerpc/boot/Makefile:198:
arch/powerpc/boot/cuboot.o] Error 1
  COPY    arch/powerpc/boot/inffixed.h
make: *** [arch/powerpc/Makefile:289: zImage] Error 2
make: *** Waiting for unfinished jobs....

With this patch applied builds fine. Please merge!

Reviewed-by: Cyril Bur <cyrilbur@gmail.com>

> ---
>  arch/powerpc/boot/Makefile | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/powerpc/boot/Makefile b/arch/powerpc/boot/Makefile
> index a7814a7b1523..6f952fe1f084 100644
> --- a/arch/powerpc/boot/Makefile
> +++ b/arch/powerpc/boot/Makefile
> @@ -25,12 +25,20 @@ compress-$(CONFIG_KERNEL_XZ)   := CONFIG_KERNEL_XZ
>  BOOTCFLAGS    := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
>  		 -fno-strict-aliasing -Os -msoft-float -pipe \
>  		 -fomit-frame-pointer -fno-builtin -fPIC -nostdinc \
> -		 -isystem $(shell $(CROSS32CC) -print-file-name=include) \
>  		 -D$(compress-y)
>  
> +BOOTCC := $(CC)
>  ifdef CONFIG_PPC64_BOOT_WRAPPER
>  BOOTCFLAGS	+= -m64
> +else
> +BOOTCFLAGS	+= -m32
> +ifdef CROSS32_COMPILE
> +    BOOTCC := $(CROSS32_COMPILE)gcc
> +endif
>  endif
> +
> +BOOTCFLAGS	+= -isystem $(shell $(BOOTCC) -print-file-name=include)
> +
>  ifdef CONFIG_CPU_BIG_ENDIAN
>  BOOTCFLAGS	+= -mbig-endian
>  else
> @@ -183,10 +191,10 @@ clean-files := $(zlib-) $(zlibheader-) $(zliblinuxheader-) \
>  		empty.c zImage.coff.lds zImage.ps3.lds zImage.lds
>  
>  quiet_cmd_bootcc = BOOTCC  $@
> -      cmd_bootcc = $(CROSS32CC) -Wp,-MD,$(depfile) $(BOOTCFLAGS) -c -o $@ $<
> +      cmd_bootcc = $(BOOTCC) -Wp,-MD,$(depfile) $(BOOTCFLAGS) -c -o $@ $<
>  
>  quiet_cmd_bootas = BOOTAS  $@
> -      cmd_bootas = $(CROSS32CC) -Wp,-MD,$(depfile) $(BOOTAFLAGS) -c -o $@ $<
> +      cmd_bootas = $(BOOTCC) -Wp,-MD,$(depfile) $(BOOTAFLAGS) -c -o $@ $<
>  
>  quiet_cmd_bootar = BOOTAR  $@
>        cmd_bootar = $(CROSS32AR) -cr$(KBUILD_ARFLAGS) $@.$$$$ $(filter-out FORCE,$^); mv $@.$$$$ $@