Re: [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.