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@xxxxxxxxxx>
> > 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@xxxxxxx>
> Reviewed-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>