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

[Michael Ellerman <mpe@ellerman.id.au>]

Christophe Leroy <christophe.leroy@csgroup.eu> writes:
> 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@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 ?

Yeah that belongs in the microwatt defconfig, not as a forced exclusion
in Kconfig.

cheers