linux-kernel - Re: [Qemu-devel] [PATCH v2 3/3] X86, mpx: Intel MPX xstate feature definition

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Message-ID: <52A274C0.4010509@zytor.com>
Date:	Fri, 06 Dec 2013 17:07:12 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	"Ren, Qiaowei" <qiaowei.ren@...el.com>,
	"Liu, Jinsong" <jinsong.liu@...el.com>,
	Paolo Bonzini <pbonzini@...hat.com>
CC:	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>,
	Xudong Hao <xudong.hao@...el.com>,
	"qemu-devel@...gnu.org" <qemu-devel@...gnu.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [Qemu-devel] [PATCH v2 3/3] X86,	mpx: Intel MPX xstate feature
 definition

On 12/06/2013 04:23 PM, Ren, Qiaowei wrote:
>>>
>>> We need to either disable these features in lazy mode, or we need to
>>> force eager mode if these features are to be supported.  The problem
>>> with the latter is that it means forcing eager mode regardless of if
>>> anything actually *uses* these features.
>>>
>>> A third option would be to require applications to use a prctl() or
>>> similar to enable eager-save features.
>>>
>>
>> The third option seems better -- how does native mpx patches work, force
>> eager?
>>
> It should be the second option, as you can see xsave.c which we remove from this patch. :)
> 

Ah yes... I missed the fact that that chunk had been dropped from this
patch.  It really shouldn't be.

I'll substitute the previous version of the patch.

	-hpa

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