Re: [PATCH RESEND 2/2] xen: Allow EXPERT mode to be selected from the menuconfig directly

[Jan Beulich <jbeulich@xxxxxxxx>]

On 04.05.2020 11:30, Julien Grall wrote:
> Hi Jan,
> 
> On 04/05/2020 10:18, Jan Beulich wrote:
>> On 30.04.2020 17:35, Julien Grall wrote:
>>> On 30/04/2020 15:50, Jan Beulich wrote:
>>>> On 30.04.2020 16:25, Julien Grall wrote:
>>>>> EXPERT mode is currently used to gate any options that are in technical
>>>>> preview or not security supported At the moment, the only way to select
>>>>> it is to use XEN_CONFIG_EXPERT=y on the make command line.
>>>>>
>>>>> However, if the user forget to add the option of one of the make
>>>>> command (even a clean), then .config will get rewritten. This may lead
>>>>> to a rather frustrating experience as it is difficult to diagnostic the
>>>>> issue.
>>>>
>>>> Is / will this still be true after Anthony's rework of the build
>>>> system? Right now we already have
>>>>
>>>> clean-targets := %clean
>>>> no-dot-config-targets := $(clean-targets) \
>>>>                            ...
>>>
>>> I haven't tried Anthony's rework yet. But I guess the problem would
>>> be the same if you forget to add XEN_CONFIG_EXPERT=y on make.
>>
>> Why? xen/.config would get re-written only if kconfig got run in
>> the first place. It is my understanding that no-dot-config-targets
>> exist to avoid including .config, and as a result make won't find
>> a need anymore to cause it to re-made if out of date.
> 
> kconfig may be executed because you change one of the */Kconfig file.
> So if you happen to forget XEN_CONFIG_EXPERT=y on your build command
> line, then you will have your .config rewritten without expert options.

That's still a build system issue then (if this is really what happens):
Dependencies of xen/.config shouldn't be evaluated as long as it doesn't
get used.

Jan