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

[Jan Beulich <jbeulich@xxxxxxxx>]

On 11.05.2020 15:30, Julien Grall wrote:
> Hi Ian,
> 
> Thank you for the clarification.
> 
> On 07/05/2020 18:01, Ian Jackson wrote:
>> Julien Grall writes ("Re: [PATCH RESEND 2/2] xen: Allow EXPERT mode to be 
>> selected from the menuconfig directly"):
>>> On 04/05/2020 13:34, Ian Jackson wrote:
>>>> George Dunlap writes ("Re: [PATCH RESEND 2/2] xen: Allow EXPERT mode to be 
>>>> selected from the menuconfig directly"):
>>>>> On Apr 30, 2020, at 3:50 PM, Jan Beulich <JBeulich@xxxxxxxx> wrote:
>>>>>> Well, if I'm not mis-remembering it was on purpose to make it more
>>>>>> difficult for people to declare themselves "experts". FAOD I'm not
>>>>>> meaning to imply I don't see and accept the frustration aspect you
>>>>>> mention further up. The two need to be carefully weighed against
>>>>>> one another.
>>>>
>>>> Yes, it was on purpose.  However, I had my doubts at the time and
>>>> I think experience has shown that this was a mistake.
>>>>
>>>>> I don’t think we need to make it difficult for people to declare
>>>>> themselves experts, particularly as “all” it means at the moment is,
>>>>> “Can build something which is not security supported”.  People who
>>>>> are building their own hypervisors are already pretty well advanced;
>>>>> I think we can let them shoot themselves in the foot if they want
>>>>> to.
>>>>
>>>> Precisely.
>>>
>>> Can I consider this as an Acked-by? :)
>>
>> I am happy with the principle of the change.  I haven't reviewed the
>> details of the commit message etc.
>>
>> I reviewed the thread and there were two concernes raised:
>>
>>   * The question of principle.  I disagree with this concern
>>     because I approve of principle of the patch.
>>
>>   * Some detail about the precise justificaton as written in
>>     the commit message, regarding `clean' targets.  Apparently the
>>     assertion may not be completely true.  I haven't seen a proposed
>>     alternative wording.
> 
> I have checked the latest staging, the `clean` target doesn't trash 
> .config anymore.
> 
>>
>> I don't feel I should ack a controversial patch with an unresolved
>> wording issue.  Can you tell me what your proposed wording is ?
>> To avoid blocking this change I would be happy to review your wording
>> and see if it meets my reading of the stated objection.
> 
> Here a suggested rewording:
> 
> "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 when (re)building or when 
> using menuconfig, then .config will get rewritten. This may lead to a 
> rather frustrating experience as it is difficult to diagnostic the
> issue.

To me this looks very similar to e.g. not suitably overriding the
default toolchain binaries, if one has a need to build with newer
ones than what a distro provides. According to some of my routinely
built configs both can be done by putting suitable entries into
./.config (not xen/.config), removing the need to remember adding
either to the make command line.

Jan