linux-kernel - Re: [PATCH v7 03/10] x86, mpx: add macro cpu_has

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Message-ID: <53CFDC79.8040804@intel.com>
Date:	Wed, 23 Jul 2014 09:02:01 -0700
From:	Dave Hansen <dave.hansen@...el.com>
To:	"Ren, Qiaowei" <qiaowei.ren@...el.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>
CC:	"x86@...nel.org" <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: Re: [PATCH v7 03/10] x86, mpx: add macro cpu_has_mpx

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/commit/?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?

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