Re: [Xen-devel] [PATCHv6] 08/28] build: convert HAS_IOPORTS use to Kconfig

[Doug Goldstein <cardoe@xxxxxxxxxx>]

On 11/30/15 9:01 AM, Jan Beulich wrote:
>>>> On 30.11.15 at 15:56, <JBeulich@xxxxxxxx> wrote:
>>>>> On 24.11.15 at 18:51, <cardoe@xxxxxxxxxx> wrote:
>>> --- a/xen/drivers/char/Kconfig
>>> +++ b/xen/drivers/char/Kconfig
>>> @@ -3,3 +3,8 @@ config UART_NS16550
>>>     bool "16550-series UART support"
>>>     help
>>>       This selects the 16550-series UART support. For most systems, say Y.
>>> +
>>> +# Select HAS_IOPORTS if 16550 has I/O ports
>>> +config HAS_IOPORTS
>>> +   bool
>>> +   depends on UART_NS16550
>>
>> Even if only used in ns16550.c, this is a generic setting and hence
>> belongs in common/Kconfig and should be selected by the arches
>> as needed.
> 
> I see it is being selected, but the "depends" here is bogus: When
> there is no prompt and no default, there should also not be any
> dependency.
> 
> Jan
> 

The dependency just means it can't be enabled unless the dependency is
met. I believe its valid for the case when the config system starts and
the user disables UART_NS16550, then HAS_IOPORTS would need to be
disabled. Without the dependency then this wouldn't be turned off when
UART_NS16550 is turned off. There are a number of examples of this in
the Linux kernel's usage of kconfig.

-- 
Doug Goldstein

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