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From:   Michael Ellerman <mpe@ellerman.id.au>
To:     Christophe Leroy <christophe.leroy@csgroup.eu>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>
Cc:     linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] powerpc/47x: Disable 256k page size
In-Reply-To: <2fed79b1154c872194f98bac4422c23918325e61.1611039590.git.christophe.leroy@csgroup.eu>
References: <2fed79b1154c872194f98bac4422c23918325e61.1611039590.git.christophe.leroy@csgroup.eu>
Date:   Wed, 20 Jan 2021 16:45:38 +1100
Message-ID: <87h7ncqhz1.fsf@mpe.ellerman.id.au>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

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?

cheers