On Monday 11 July 2022 16:19:30 Christophe Leroy wrote:
> Since commit 4bf4f42a2feb ("powerpc/kbuild: Set default generic
> machine type for 32-bit compile"), when building a 32 bits kernel
> with a bi-arch version of GCC, or when building a book3s/32 kernel,
> the option -mcpu=powerpc is passed to GCC at all time, relying on it
> being eventually overriden by a subsequent -mcpu=xxxx.
>
> But when building the same kernel with a 32 bits only version of GCC,
> that is not done, relying on gcc being built with the expected default
> CPU.
>
> This logic has two problems. First, it is a bit fragile to rely on
> whether the GCC version is bi-arch or not, because today we can have
> bi-arch versions of GCC configured with a 32 bits default. Second,
> there are some versions of GCC which don't support -mcpu=powerpc,
> for instance for e500 SPE-only versions.
>
> So, stop relying on this approximative logic and allow the user to
> decide whether he/she wants to use the toolchain's default CPU or if
> he/she wants to set one, and allow only possible CPUs based on the
> selected target.
Hello! Exactly same issue is still in file arch/powerpc/boot/Makefile:
ifdef CONFIG_PPC64_BOOT_WRAPPER
ifdef CONFIG_CPU_LITTLE_ENDIAN
BOOTCFLAGS += -m64 -mcpu=powerpc64le
else
BOOTCFLAGS += -m64 -mcpu=powerpc64
endif
else
BOOTCFLAGS += -m32 -mcpu=powerpc
endif
It cause compile error:
make ARCH=powerpc CROSS_COMPILE=powerpc-linux-gnuspe- mpc85xx_smp_defconfig
uImage
...
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
> Reported-by: Pali Rohár <p...@kernel.org>
> Tested-by: Pali Rohár <p...@kernel.org>
> Reviewed-by: Arnd Bergmann <a...@arndb.de>
> Cc: Segher Boessenkool <seg...@kernel.crashing.org>
> Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu>
> ---
> arch/powerpc/Makefile | 26 +-------------------------
> arch/powerpc/platforms/Kconfig.cputype | 21 ++++++++++++++++++---
> 2 files changed, 19 insertions(+), 28 deletions(-)
