On 24 July 2018 at 10:12, Arnd Bergmann <arnd@xxxxxxxx> wrote:
> On Tue, Jul 24, 2018 at 2:26 AM, AKASHI Takahiro
> <takahiro.akashi@xxxxxxxxxx> wrote:
>> On Tue, Jul 24, 2018 at 09:05:45AM +1000, Stephen Rothwell wrote:
>>> Hi all,
>>>
>>> After merging the arm64 tree, today's linux-next build (x86_64
>>> allmodconfig) produced this warning:
>>
>> Where can I find this specific branch?
>>
>>> drivers/acpi/Kconfig:6:error: recursive dependency detected!
>>> drivers/acpi/Kconfig:6: symbol ACPI depends on EFI
>>
>> My patch created an additional dependency like:
>> menu ACPI
>> ...
>> depends on IA64 || X86 || (ARM64 && EFI)
>>
>>> arch/x86/Kconfig:1920: symbol EFI depends on ACPI
>>
>> So I don't understand why this change makes a warning on x86_64 build.
>> Is this a real recursive dependency?
>
> On x86, we have
>
> config EFI
> bool "EFI runtime service support"
> depends on ACPI
>
> Kconfig cannot know that CONFIG_ARM64 is never set on x86, while
> X86 is always set. So to Kconfig it it appears like a recursive
> dependency.
>
> The best workaround I can see is to have an intermediate symbol
> on ARM64 that is invisible to Kconfig on x86, like
>
> config ARCH_SUPPORTS_ACPI
> def_bool EFI
>
> and then have ACPI depend on that.
>
I suppose you mean
depends on IA64 || X86 || ARCH_SUPPORTS_ACPI
right?
Instead, perhaps we could have
config ARCH_SUPPORTS_ACPI
def_bool IA64 || X86
and make CONFIG_ACPI depend on that. Then, we can set it conditionally
in arch/arm64/Kconfig if CONFIG_EFI is enabled.
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