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Re: [PATCH v2] xen: EXPERT clean-up and introduce UNSUPPORTED
- To: Jan Beulich <jbeulich@xxxxxxxx>
- From: Bertrand Marquis <Bertrand.Marquis@xxxxxxx>
- Date: Wed, 18 Nov 2020 14:23:13 +0000
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- Cc: "open list:X86" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Stefano Stabellini <stefano.stabellini@xxxxxxxxxx>, "andrew.cooper3@xxxxxxxxxx" <andrew.cooper3@xxxxxxxxxx>, "george.dunlap@xxxxxxxxxx" <george.dunlap@xxxxxxxxxx>, "iwj@xxxxxxxxxxxxxx" <iwj@xxxxxxxxxxxxxx>, "julien@xxxxxxx" <julien@xxxxxxx>, "wl@xxxxxxx" <wl@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>
- Delivery-date: Wed, 18 Nov 2020 14:23:46 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
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- Thread-topic: [PATCH v2] xen: EXPERT clean-up and introduce UNSUPPORTED
Hi Jan,
> On 18 Nov 2020, at 08:50, Jan Beulich <jbeulich@xxxxxxxx> wrote:
>
> On 18.11.2020 09:45, Bertrand Marquis wrote:
>>> On 18 Nov 2020, at 00:50, Stefano Stabellini <sstabellini@xxxxxxxxxx> wrote:
>>> --- a/xen/arch/x86/Kconfig
>>> +++ b/xen/arch/x86/Kconfig
>>> @@ -102,8 +102,8 @@ config HVM
>>> If unsure, say Y.
>>>
>>> config XEN_SHSTK
>>> - bool "Supervisor Shadow Stacks"
>>> - depends on HAS_AS_CET_SS && EXPERT
>>> + bool "Supervisor Shadow Stacks (UNSUPPORTED)"
>>> + depends on HAS_AS_CET_SS && UNSUPPORTED
>>
>> This one is not following the standard scheme with “if UNSUPPORTED"
>
> There's no standard scheme here: There's one case where the entire
> option depends on some other setting (e.g. UNSUPPORTED) and another
> where just the prompt (i.e. giving the user a choice) does. The
> difference becomes obvious when the option has a default other than
> "no": Despite the invisible prompt, it may get turned on. In the
> case here (serving as a good example), "default y" would mean the
> feature gets turned on when "if UNSUPPORTED" would be added to the
> prompt and when UNSUPPORTED is itself off.
>
It makes sense, thanks for the explanation
Bertrand
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