[RFC PATCH 6/6] powerpc/microwatt: Stop building the hash MMU code

[Christophe Leroy]

Le 27/08/2021 à 18:34, Nicholas Piggin a écrit :
> Microwatt is radix-only, so stop selecting the hash MMU code.
> 
> This saves 20kB compressed dtbImage and 56kB vmlinux size.
> 
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
> ---
>   arch/powerpc/configs/microwatt_defconfig | 1 -
>   arch/powerpc/platforms/Kconfig.cputype   | 1 +
>   arch/powerpc/platforms/microwatt/Kconfig | 1 -
>   3 files changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/configs/microwatt_defconfig b/arch/powerpc/configs/microwatt_defconfig
> index bf5f2e5905eb..6fbad42f9e3d 100644
> --- a/arch/powerpc/configs/microwatt_defconfig
> +++ b/arch/powerpc/configs/microwatt_defconfig
> @@ -26,7 +26,6 @@ CONFIG_PPC_MICROWATT=y
>   # CONFIG_PPC_OF_BOOT_TRAMPOLINE is not set
>   CONFIG_CPU_FREQ=y
>   CONFIG_HZ_100=y
> -# CONFIG_PPC_MEM_KEYS is not set
>   # CONFIG_SECCOMP is not set
>   # CONFIG_MQ_IOSCHED_KYBER is not set
>   # CONFIG_COREDUMP is not set
> diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype
> index 9b90fc501ed4..b9acd6c68c81 100644
> --- a/arch/powerpc/platforms/Kconfig.cputype
> +++ b/arch/powerpc/platforms/Kconfig.cputype
> @@ -371,6 +371,7 @@ config SPE
>   config PPC_64S_HASH_MMU
>   	bool "Hash MMU Support"
>   	depends on PPC_BOOK3S_64
> +	depends on !PPC_MICROWATT

Do we really want to start nit picking which platforms can select such or such option ?
Isn't it enough to get it off through the defconfig ?

Is PPC_MICROWATT mutually exclusive with other book3s64 configs ? Don't we build multiplatform kernels ?

>   	default y
>   	select PPC_MM_SLICES
>   	help
> diff --git a/arch/powerpc/platforms/microwatt/Kconfig b/arch/powerpc/platforms/microwatt/Kconfig
> index e0ff2cfc1ca0..4f0ce292a6ce 100644
> --- a/arch/powerpc/platforms/microwatt/Kconfig
> +++ b/arch/powerpc/platforms/microwatt/Kconfig
> @@ -6,7 +6,6 @@ config PPC_MICROWATT
>   	select PPC_XICS
>   	select PPC_ICS_NATIVE
>   	select PPC_ICP_NATIVE
> -	select PPC_HASH_MMU_NATIVE if PPC_64S_HASH_MMU
>   	select PPC_UDBG_16550
>   	select ARCH_RANDOM
>   	help
>