Re: [PATCH v3] powerpc/boot: Don't always pass -mcpu=powerpc when building 32-bit uImage

["Pali Rohár" <pali@kernel.org>]

On Sunday 28 August 2022 17:39:25 Christophe Leroy wrote:
> Le 28/08/2022 à 19:33, Christophe Leroy a écrit :
> > 
> > 
> > Le 28/08/2022 à 11:56, Pali Rohár a écrit :
> >> When CONFIG_TARGET_CPU is specified then pass its value to the compiler
> >> -mcpu option. This fixes following build error when building kernel with
> >> powerpc e500 SPE capable cross compilers:
> >>
> >>      BOOTAS  arch/powerpc/boot/crt0.o
> >>    powerpc-linux-gnuspe-gcc: error: unrecognized argument in option 
> >> ‘-mcpu=powerpc’
> >>    powerpc-linux-gnuspe-gcc: note: valid arguments to ‘-mcpu=’ are: 
> >> 8540 8548 native
> >>    make[1]: *** [arch/powerpc/boot/Makefile:231: 
> >> arch/powerpc/boot/crt0.o] Error 1
> > 
> > corenet64_smp_defconfig :
> > 
> >    BOOTAS  arch/powerpc/boot/crt0.o
> > powerpc64-linux-gcc: error: missing argument to '-mcpu='
> > make[1]: *** [arch/powerpc/boot/Makefile:237 : arch/powerpc/boot/crt0.o] 
> > Erreur 1
> > make: *** [arch/powerpc/Makefile:253 : uImage] Erreur 2
> > 
> > 
> 
> Seems like in fact, E5500_CPU and E6500_CPU are not taken into account 
> in CONFIG_TARGET_CPU, and get special treatment directly in 
> arch/powerpc/Makefile.
> 
> This goes unnoticed because of CFLAGS-$(CONFIG_TARGET_CPU_BOOL) += 
> $(call cc-option,-mcpu=$(CONFIG_TARGET_CPU))
> 
> I think we need to fix that prior to your patch.

It looks like that CONFIG_TARGET_CPU is broken.

  $ make ARCH=powerpc corenet64_smp_defconfig CROSS_COMPILE=powerpc64-linux-gnu-
  ...
  # configuration written to .config

  $ grep CONFIG_TARGET_CPU .config
  CONFIG_TARGET_CPU_BOOL=y

CONFIG_TARGET_CPU_BOOL is set but CONFIG_TARGET_CPU not!

> > Christophe
> > 
> > 
> >>
> >> Similar change was already introduced for the main powerpc Makefile in
> >> commit 446cda1b21d9 ("powerpc/32: Don't always pass -mcpu=powerpc to the
> >> compiler").
> >>
> >> Fixes: 40a75584e526 ("powerpc/boot: Build wrapper for an appropriate 
> >> CPU")
> >> Cc: stable@vger.kernel.org # 446cda1b21d9 ("powerpc/32: Don't always 
> >> pass -mcpu=powerpc to the compiler")
> >> Signed-off-by: Pali Rohár <pali@kernel.org>
> >> ---
> >>   arch/powerpc/boot/Makefile | 14 ++++++++++----
> >>   1 file changed, 10 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/arch/powerpc/boot/Makefile b/arch/powerpc/boot/Makefile
> >> index a9cd2ea4a861..1957a3de7a1c 100644
> >> --- a/arch/powerpc/boot/Makefile
> >> +++ b/arch/powerpc/boot/Makefile
> >> @@ -38,13 +38,19 @@ BOOTCFLAGS    := -Wall -Wundef -Wstrict-prototypes 
> >> -Wno-trigraphs \
> >>            $(LINUXINCLUDE)
> >>   ifdef CONFIG_PPC64_BOOT_WRAPPER
> >> -ifdef CONFIG_CPU_LITTLE_ENDIAN
> >> -BOOTCFLAGS    += -m64 -mcpu=powerpc64le
> >> +BOOTCFLAGS    += -m64
> >>   else
> >> -BOOTCFLAGS    += -m64 -mcpu=powerpc64
> >> +BOOTCFLAGS    += -m32
> >>   endif
> >> +
> >> +ifdef CONFIG_TARGET_CPU_BOOL
> >> +BOOTCFLAGS    += -mcpu=$(CONFIG_TARGET_CPU)
> >> +else ifdef CONFIG_PPC64_BOOT_WRAPPER
> >> +ifdef CONFIG_CPU_LITTLE_ENDIAN
> >> +BOOTCFLAGS    += -mcpu=powerpc64le
> >>   else
> >> -BOOTCFLAGS    += -m32 -mcpu=powerpc
> >> +BOOTCFLAGS    += -mcpu=powerpc64
> >> +endif
> >>   endif
> >>   BOOTCFLAGS    += -isystem $(shell $(BOOTCC) -print-file-name=include)