Re: [RFC PATCH 1/5] hw/mem/nvdimm: Use Kconfig 'imply' instead of 'depends on'

[Philippe Mathieu-Daudé]

On 5/12/21 6:53 AM, Thomas Huth wrote:
> On 12/05/2021 05.57, Philippe Mathieu-Daudé wrote:
>> On 5/12/21 4:24 AM, David Gibson wrote:
>>> On Tue, May 11, 2021 at 05:53:50PM +0200, Philippe Mathieu-Daudé wrote:
>>>> Per the kconfig.rst:
>>>>
>>>>    A device should be listed [...] ``imply`` if (depending on
>>>>    the QEMU command line) the board may or  may not be started
>>>>    without it.
>>>>
>>>> This is the case with the NVDIMM device, so use the 'imply'
>>>> weak reverse dependency to select the symbol.
>>>
>>> Uh.. It should definitely be possible to start a pseries machine
>>> without NVDIMM.  I would have guessed the same for PC.
>>
>> Yes, this is what this patch does. With it we can build with:
>> CONFIG_NVDIMM=n
> 
> But with "imply" you could end up with a PSERIES that does not have
> NVDIMM when also using --without-default-devices, couldn't you?

Not currently, because of the CONFIG_NVDIMM=y.

> Why don't you use "select" instead of "imply" ?

Because as David said earlier:

"It should definitely be possible to start a pseries machine
without NVDIMM."