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

[Jan Beulich <jbeulich@xxxxxxxx>]

On 12.05.2020 13:00, Julien Grall wrote:
> Hi Jan,
> 
> On 12/05/2020 11:15, Jan Beulich wrote:
>> On 12.05.2020 12:08, Julien Grall wrote:
>>> On 12/05/2020 08:18, Jan Beulich wrote:
>>>> On 11.05.2020 19:14, Ian Jackson wrote:
>>>>> Jan Beulich writes ("Re: [PATCH RESEND 2/2] xen: Allow EXPERT mode to be 
>>>>> selected from the menuconfig directly"):
>>>>>> I'm trying to make the point that your patch, to me, looks to be
>>>>>> trying to overcome a problem for which we have had a solution all
>>>>>> the time.
>>>>>
>>>>> Thanks for this clear statement of your objection.  I'm afraid I don't
>>>>> agree.  Even though .config exists (and is even used by osstest, so I
>>>>> know about it) I don't think it is as good as having it in
>>>>> menuconfig.
>>>>
>>>> But you realize that my objection is (was) more towards the reasoning
>>>> behind the change, than towards the change itself. If, as a community,
>>>> we decide to undo what we might now call a mistake, and if we're ready
>>>> to deal with the consequences, so be it.
>>>
>>> Would you mind to explain the fall out you expect from this patch? Are
>>> you worry more people may contact security@xxxxxxx for non-security issue?
>>
>> That's one possible thing that might happen. But even more generally
>> the likelihood will increase that people report issues without paying
>> attention that they depend on their choice of configuration.
> I agree that you are going to get more report because there are more 
> users to try new things. So inevitently, you will get more incomplete 
> report. This is always the downside of allowing more flexibility.
> 
> But we also need to look at the upside. I can see 2 advantages:
>      1) It will be easier to try upcoming features (e.g Argo). The more 
> testing and input, the more chance a feature will be a success.
>      2) It will be easier to tailor Xen (such as built-in command line).
> 
> In both cases, you make Xen more compelling because you allow to 
> experiment and make it more flexible. IHMO, this is one of the best way 
> to attract users and possible new contributors/reviewers to Xen community.

I'm fully aware of the upsides.

>>  We'll
>> have to both take this into consideration and ask back for the
>> specific .config they've used.
> Correct me if I am wrong, but this is not very specific to EXPERT mode. 
> You can already select different options that will affect the behavior 
> of the hypervisor. For instance, on x86, you can disable PV guest 
> support. How do you figure that out today without asking the .config?

I didn't say this is a new problem; I indicated this is going to
become more likely to be one.

Jan