Re: Kconfig circular dependency question

[Larry Finger <Larry.Finger@lwfinger.net>]

On 04/06/2014 03:31 PM, Randy Dunlap wrote:
> On 04/06/2014 12:49 PM, Larry Finger wrote:
>> A kernel build is reporting the following:
>>
>> net/rfkill/Kconfig:4:error: recursive dependency detected!
>> net/rfkill/Kconfig:4:   symbol RFKILL is selected by R8723AU
>> drivers/staging/rtl8723au/Kconfig:1:    symbol R8723AU depends on USB
>> drivers/usb/Kconfig:41: symbol USB is selected by MOUSE_APPLETOUCH
>> drivers/input/mouse/Kconfig:162:        symbol MOUSE_APPLETOUCH depends on INPUT
>> drivers/input/Kconfig:8:        symbol INPUT is selected by ACPI_CMPC
>> drivers/platform/x86/Kconfig:635:       symbol ACPI_CMPC depends on RFKILL
>>
>> What is the recommended way to avoid this circularity? Of course, R8723AU could select USB rather than depending on it, but that does not seem quite right.
>
> I don't know if it will fix the problem, but Linus has spoken (written)
> against selecting subsystems, like INPUT or USB.
>
> Does changing ACPI_CMPC to depend on INPUT instead of select INPUT
> help?
> and/or changing MOUSE_APPLETOUCH to depend on USB instead of select it?

This case seems to prove why Linus has so spoken!

Changing ACPI_CMPC to depend on INPUT does fix the build. Making the change to 
MOUSE_APPLETOUCH ends up getting a different recursive error.

Thanks for your suggestion. As I do not "own" the x86 platform drivers, I will 
have to post a patch to fix the ACPI_CMPC problem, but at least I know what to 
say in the commit message that adds the RFKILL selection to the R8723AU Kconfig.

Larry