Re: [Xen-devel] [PATCH for-4.13 2/2] xen/nospec: Introduce CONFIG_SPECULATIVE_BRANCH_HARDEN and disable it

[Jan Beulich <jbeulich@xxxxxxxx>]

On 01.10.2019 11:17, Julien Grall wrote:
> On 01/10/2019 00:21, Andrew Cooper wrote:
>> On 30/09/2019 21:17, Julien Grall wrote:
>>> My worry is this gate config gate nothing on Arm so the user may have
>>> a false sense that it can be used (even though it is clearly BROKEN).
>>>
>>> Also the name is quite close to the CONFIG_HARDEN_PREDICTOR on Arm and
>>> may confuse user. Although, I don't have a better name so far :/
>>
>> The "depends on BROKEN" means it will never show up to a user in
>> menuconfig, which is why it was only CC to x86, and not to rest.
> 
> What's the long term plan for this option? Are you planning to remove it 
> completely or just the dependencies on BROKEN?
> 
> My concern is if this option will ever become selectable then it will not 
> doing 
> what's expected on Arm.
> 
> So, even if in principle it is arch agnostic, it feels to me this option 
> should 
> better be implemented in x86/Kconfig.

I don't think so, no. When BROKEN is to be removed, it ought to be
replaced by a suitable "depends on HAVE_*", which Arm could choose
to not select.

Jan

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