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Date:   Fri, 4 Aug 2023 13:48:19 +0100
From:   Catalin Marinas <catalin.marinas@arm.com>
To:     Zhang Jianhua <chris.zjh@huawei.com>
Cc:     will@kernel.org, ardb@kernel.org, mark.rutland@arm.com,
        ryan.roberts@arm.com, anshuman.khandual@arm.com,
        joey.gouly@arm.com, thunder.leizhen@huawei.com, bhe@redhat.com,
        kristina.martsenko@arm.com, yajun.deng@linux.dev,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH -next v4] arm64: fix build warning for
 ARM64_MEMSTART_SHIFT
Message-ID: <ZMzzkyc0M9y29yWw@arm.com>
References: <20230804075615.3334756-1-chris.zjh@huawei.com>
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On Fri, Aug 04, 2023 at 03:56:15PM +0800, Zhang Jianhua wrote:
> When building with W=1, the following warning occurs.
> 
> arch/arm64/include/asm/kernel-pgtable.h:129:41: error: "PUD_SHIFT" is not defined, evaluates to 0 [-Werror=undef]
>   129 | #define ARM64_MEMSTART_SHIFT            PUD_SHIFT
>       |                                         ^~~~~~~~~
> arch/arm64/include/asm/kernel-pgtable.h:142:5: note: in expansion of macro ‘ARM64_MEMSTART_SHIFT’
>   142 | #if ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS
>       |     ^~~~~~~~~~~~~~~~~~~~
> 
> The generic PUD_SHIFT was defined in include/asm-generic/pgtable-nopud.h,
> however the #ifndef __ASSEMBLY__ guard in this header file makes it unavailable
> for assembly files. While someone .S file include the <asm/kernel-pgtable.h>,
> the build warning would occur. Now move the macro ARM64_MEMSTART_SHIFT and
> ARM64_MEMSTART_ALIGN to arch/arm64/mm/init.c where it is used only, to avoid
> this issue.
> 
> Signed-off-by: Zhang Jianhua <chris.zjh@huawei.com>

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>