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

[Nicholas Piggin]

Excerpts from Michael Ellerman's message of August 30, 2021 1:24 pm:
> Christophe Leroy <christophe.leroy at 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 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 ?
> 
> Yeah that belongs in the microwatt defconfig, not as a forced exclusion
> in Kconfig.

Okay I'll fix that up. In that case the select POWER9 should not be in 
Kconfig but just defconfig too. Which is fine, it just means oldconfig
won't change it.

Thanks,
Nick