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Date: Fri, 06 Dec 2013 17:07:12 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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Subject: Re: [Qemu-devel] [PATCH v2 3/3] X86,
 mpx: Intel MPX xstate feature definition
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To: "Ren, Qiaowei" <qiaowei.ren@intel.com>, "Liu, Jinsong" <jinsong.liu@intel.com>, Paolo Bonzini <pbonzini@redhat.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>, "x86@kernel.org" <x86@kernel.org>, Xudong Hao <xudong.hao@intel.com>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@kernel.org>

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