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Subject: Re: [PATCH] powerpc/47x: Disable 256k page size
To:     Michael Ellerman <mpe@ellerman.id.au>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>
Cc:     linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
References: <2fed79b1154c872194f98bac4422c23918325e61.1611039590.git.christophe.leroy@csgroup.eu>
 <87h7ncqhz1.fsf@mpe.ellerman.id.au>
From:   Christophe Leroy <christophe.leroy@csgroup.eu>
Message-ID: <19acabee-3a6d-d2d0-db7a-b637bd162069@csgroup.eu>
Date:   Wed, 20 Jan 2021 07:31:35 +0100
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Le 20/01/2021 à 06:45, Michael Ellerman a écrit :
> Christophe Leroy <christophe.leroy@csgroup.eu> writes:
>> PPC47x_TLBE_SIZE isn't defined for 256k pages, so
>> this size of page shall not be selected for 47x.
>>
>> Reported-by: kernel test robot <lkp@intel.com>
>> Fixes: e7f75ad01d59 ("powerpc/47x: Base ppc476 support")
>> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
>> ---
>>   arch/powerpc/Kconfig | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
>> index 107bb4319e0e..a685e42d3993 100644
>> --- a/arch/powerpc/Kconfig
>> +++ b/arch/powerpc/Kconfig
>> @@ -772,7 +772,7 @@ config PPC_64K_PAGES
>>   
>>   config PPC_256K_PAGES
>>   	bool "256k page size"
>> -	depends on 44x && !STDBINUTILS
>> +	depends on 44x && !STDBINUTILS && !PPC_47x
> 
> Do we still need this STDBINUTILS thing?
> 
> It's pretty gross, and I notice we have zero defconfigs which disable
> it, meaning it's only randconfig builds that will ever test 256K pages.
> 
> Can we just drop it and say if you enable 256K pages you need to know
> what you're doing?

I guess we can, yes. I'll send a patch for that.

Christophe

>