Re: [PATCH -next v3] arm64: fix build warning for ARM64_MEMSTART_SHIFT

Re: [PATCH -next v3] arm64: fix build warning for ARM64_MEMSTART_SHIFT

[Catalin Marinas]

On Tue, Jul 25, 2023 at 08:24:04PM +0000, 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 reason is that PUD_SHIFT isn't defined if CONFIG_PGTABLE_LEVELS == 3
> and CONFIG_VA_BITS == 39.

The correct description is that the generic PUD_SHIFT isn't defined for
asm files, we still have it defined for C files (there's an #ifndef
__ASSEMBLY__ guard).

> Now move the macro ARM64_MEMSTART_SHIFT and
> ARM64_MEMSTART_ALIGN to arch/arm64/mm/init.c where it is used to avoid
> this issue, and also there is no other place to call these two macro.
> 
> Signed-off-by: Zhang Jianhua <chris.zjh@huawei.com>

This fix works for me. I'll leave it to Will for 6.6 as apart from the
warning with W=1, there's no other issue (ARM64_MEMSTART_* are not used
in any asm files).

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

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Re: [PATCH -next v3] arm64: fix build warning for ARM64_MEMSTART_SHIFT

[Anshuman Khandual]

On 8/3/23 22:36, Catalin Marinas wrote:
> On Tue, Jul 25, 2023 at 08:24:04PM +0000, 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 reason is that PUD_SHIFT isn't defined if CONFIG_PGTABLE_LEVELS == 3
>> and CONFIG_VA_BITS == 39.
> 
> The correct description is that the generic PUD_SHIFT isn't defined for
> asm files, we still have it defined for C files (there's an #ifndef
> __ASSEMBLY__ guard).

Agreed, please rework the commit message explaining how generic PUD_SHIFT
definition is not available for assembly files, prompting this code block
movement. CONFIG_PGTABLE_LEVELS == 3 with CONFIG_VA_BITS == 39 just help
in exposing this problem.

> 
>> Now move the macro ARM64_MEMSTART_SHIFT and
>> ARM64_MEMSTART_ALIGN to arch/arm64/mm/init.c where it is used to avoid
>> this issue, and also there is no other place to call these two macro.
>>
>> Signed-off-by: Zhang Jianhua <chris.zjh@huawei.com>
> 
> This fix works for me. I'll leave it to Will for 6.6 as apart from the
> warning with W=1, there's no other issue (ARM64_MEMSTART_* are not used
> in any asm files).

Right, not real a problem to be fixed, this can wait till 6.6

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

Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>

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Re: [PATCH -next v3] arm64: fix build warning for ARM64_MEMSTART_SHIFT

[zhangjianhua (E)]

在 2023/8/4 14:24, Anshuman Khandual 写道:
>
> On 8/3/23 22:36, Catalin Marinas wrote:
>> On Tue, Jul 25, 2023 at 08:24:04PM +0000, 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 reason is that PUD_SHIFT isn't defined if CONFIG_PGTABLE_LEVELS == 3
>>> and CONFIG_VA_BITS == 39.
>> The correct description is that the generic PUD_SHIFT isn't defined for
>> asm files, we still have it defined for C files (there's an #ifndef
>> __ASSEMBLY__ guard).
> Agreed, please rework the commit message explaining how generic PUD_SHIFT
> definition is not available for assembly files, prompting this code block
> movement. CONFIG_PGTABLE_LEVELS == 3 with CONFIG_VA_BITS == 39 just help
> in exposing this problem.
No problem, I will send a new patch soon.
>>> Now move the macro ARM64_MEMSTART_SHIFT and
>>> ARM64_MEMSTART_ALIGN to arch/arm64/mm/init.c where it is used to avoid
>>> this issue, and also there is no other place to call these two macro.
>>>
>>> Signed-off-by: Zhang Jianhua <chris.zjh@huawei.com>
>> This fix works for me. I'll leave it to Will for 6.6 as apart from the
>> warning with W=1, there's no other issue (ARM64_MEMSTART_* are not used
>> in any asm files).
> Right, not real a problem to be fixed, this can wait till 6.6
>
>> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
>

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