[PATCH] acpi: Fix header declaration of acpi_arch_dma_setup() w/o CONFIG_ACPI

[Robin Murphy]

On 2023-06-01 02:48, Hanjun Guo wrote:
> Hi Dave,
> 
> Sorry for the late reply, I have some comments inline.
> 
> On 2023/5/23 0:06, Dave Jiang wrote:
>> arm64 build can be done without CONFIG_ACPI. The ifdef bits for
>> acpi_arch_dma_setup() is placed inside CONFIG_ACPI. When CONFIG_ACPI is
>> not set, this causes warning reported by kernel test bot. Move the
>> prototype declaration for acpi_arch_dma_setup() outside of CONFIG_ACPI.
> 
> ...
> 
>>
>>>> drivers/acpi/arm64/dma.c:7:6: warning: no previous prototype for 
>>>> function 'acpi_arch_dma_setup' [-Wmissing-prototypes]
>>     void acpi_arch_dma_setup(struct device *dev)
>>          ^
>>     drivers/acpi/arm64/dma.c:7:1: note: declare 'static' if the 
>> function is not intended to be used outside of this translation unit
>>     void acpi_arch_dma_setup(struct device *dev)
>>     ^
>>     static
>>     1 warning generated.
> 
> drivers/acpi can only be compiled with CONFIG_ACPI=y, so
> drivers/acpi/arm64/ will be the same, not sure how to trigger
> this compile warning.
> 
> I disable CONFIG_ACPI on my ARM64 machine, but didn't get the
> warning you reported.

Looking at the linked LKP report, it seems it's it's explicitly trying 
to build drivers/acpi/arm64/ despite the config:

         mkdir build_dir && cp config build_dir/.config
         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 
O=build_dir ARCH=arm64 olddefconfig
         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 
O=build_dir ARCH=arm64 SHELL=/bin/bash drivers/acpi/arm64/

So I guess it's a problem with the LKP setup? In general, trying to 
build arbitrary parts of the kernel which are configured out can never 
be expected to work.

Thanks,
Robin.