Re: [PATCH v1 5/5] powerpc/64e: Fix build failure with GCC 12 (unrecognized opcode: `wrteei')

["Pali Rohár" <pali@kernel.org>]

On Monday 11 July 2022 16:19:33 Christophe Leroy wrote:
> With GCC 12, corenet64_smp_defconfig leads to the following build errors:
> 
>   CC      arch/powerpc/kernel/irq.o
> {standard input}: Assembler messages:
> {standard input}:3616: Error: unrecognized opcode: `wrteei'
> {standard input}:5689: Error: unrecognized opcode: `wrteei'
>   CC      arch/powerpc/kernel/pmc.o
> {standard input}: Assembler messages:
> {standard input}:42: Error: unrecognized opcode: `mfpmr'
> {standard input}:53: Error: unrecognized opcode: `mtpmr'
>   CC      arch/powerpc/kernel/io.o
> {standard input}: Assembler messages:
> {standard input}:376: Error: unrecognized opcode: `mbar'
> ...
>   CC      arch/powerpc/mm/nohash/book3e_hugetlbpage.o
> {standard input}: Assembler messages:
> {standard input}:291: Error: unrecognized opcode: `tlbsx'
> {standard input}:482: Error: unrecognized opcode: `tlbwe'
> {standard input}:608: Error: unrecognized opcode: `lbarx'
> {standard input}:608: Error: unrecognized opcode: `stbcx.'
> 
> -mpcu=powerpc64 cannot be used anymore for book3e, it must be a booke CPU.
> 
> But then we get:
> 
>   CC      arch/powerpc/lib/xor_vmx.o
> cc1: error: AltiVec not supported in this target
> 
> Altivec is not supported with -mcpu=e5500 so don't allow selection
> of altivec when e5500 is selected.
> 
> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
> ---
>  arch/powerpc/Makefile                  | 8 +-------
>  arch/powerpc/platforms/Kconfig.cputype | 8 ++++----
>  2 files changed, 5 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
> index d54e1fe03551..02742facf895 100644
> --- a/arch/powerpc/Makefile
> +++ b/arch/powerpc/Makefile
> @@ -168,13 +168,7 @@ endif
>  CFLAGS-$(CONFIG_TARGET_CPU_BOOL) += $(call cc-option,-mcpu=$(CONFIG_TARGET_CPU))
>  AFLAGS-$(CONFIG_TARGET_CPU_BOOL) += $(call cc-option,-mcpu=$(CONFIG_TARGET_CPU))
>  
> -# Altivec option not allowed with e500mc64 in GCC.
> -ifdef CONFIG_ALTIVEC
> -E5500_CPU := -mcpu=powerpc64
> -else
> -E5500_CPU := $(call cc-option,-mcpu=e500mc64,-mcpu=powerpc64)
> -endif
> -CFLAGS-$(CONFIG_E5500_CPU) += $(E5500_CPU)
> +CFLAGS-$(CONFIG_E5500_CPU) += $(call cc-option,-mcpu=e500mc64,-mcpu=powerpc64)
>  CFLAGS-$(CONFIG_E6500_CPU) += $(call cc-option,-mcpu=e6500,$(E5500_CPU))

Hello! I think that there is an issue. After removal of E5500_CPU
variable few line above, it cannot be used in CFLAGS-$(CONFIG_E6500_CPU)
assignment, because it is empty.

>  
>  asinstr := $(call as-instr,lis 9$(comma)foo@high,-DHAVE_AS_ATHIGH=1)
> diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
> index 3cc8452b8660..5185d942b455 100644
> --- a/arch/powerpc/platforms/Kconfig.cputype
> +++ b/arch/powerpc/platforms/Kconfig.cputype
> @@ -126,12 +126,12 @@ choice
>  
>  config GENERIC_CPU
>  	bool "Generic (POWER4 and above)"
> -	depends on PPC64 && !CPU_LITTLE_ENDIAN
> -	select PPC_64S_HASH_MMU if PPC_BOOK3S_64
> +	depends on PPC_BOOK3S_64 && !CPU_LITTLE_ENDIAN
> +	select PPC_64S_HASH_MMU
>  
>  config GENERIC_CPU
>  	bool "Generic (POWER8 and above)"
> -	depends on PPC64 && CPU_LITTLE_ENDIAN
> +	depends on PPC_BOOK3S_64 && CPU_LITTLE_ENDIAN
>  	select ARCH_HAS_FAST_MULTIPLIER
>  	select PPC_64S_HASH_MMU
>  
> @@ -358,7 +358,7 @@ config PHYS_64BIT
>  
>  config ALTIVEC
>  	bool "AltiVec Support"
> -	depends on PPC_BOOK3S_32 || PPC_BOOK3S_64 || (PPC_E500MC && PPC64)
> +	depends on PPC_BOOK3S || (PPC_E500MC && PPC64 && !E5500_CPU)
>  	select PPC_FPU
>  	help
>  	  This option enables kernel support for the Altivec extensions to the
> -- 
> 2.36.1
>