Re: [PATCH v7 03/10] x86, mpx: add macro cpu_has_mpx

From: Dave Hansen
Date: Thu Jul 24 2014 - 00:46:35 EST


On 07/23/2014 05:56 PM, Ren, Qiaowei wrote:
> On 2014-07-24, Hansen, Dave wrote:
>> On 07/22/2014 07:35 PM, Ren, Qiaowei wrote:
>>> The checking about MPX feature should be as follow:
>>>
>>> if (pcntxt_mask & XSTATE_EAGER) {
>>> if (eagerfpu == DISABLE) {
>>> pr_err("eagerfpu not present, disabling some
>> xstate features: 0x%llx\n",
>>> pcntxt_mask &
>> XSTATE_EAGER);
>>> pcntxt_mask &= ~XSTATE_EAGER; } else { eagerfpu
>>> = ENABLE;
>>> }
>>> }
>>> This patch was merged into kernel the ending of last year
>>> (https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/com
>>> mi
>>> t/?id=e7d820a5e549b3eb6c3f9467507566565646a669 )
>>
>> Should we be doing a clear_cpu_cap(X86_FEATURE_MPX) in here?
>>
>> This isn't major, but I can't _ever_ imagine a user being able to
>> track down why MPX is not working from this message. Should we
>> spruce it up somehow?
>
> Maybe. If the error log "disabling some xstate features:" is changed
> to "disabling MPX xstate features:", do you think it is OK?

That's better. Is it really disabling MPX, though?

And shouldn't we clear the cpu feature bit too?
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