From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757933Ab3LGBHu (ORCPT ); Fri, 6 Dec 2013 20:07:50 -0500 Received: from terminus.zytor.com ([198.137.202.10]:34765 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751441Ab3LGBHs (ORCPT ); Fri, 6 Dec 2013 20:07:48 -0500 Message-ID: <52A274C0.4010509@zytor.com> Date: Fri, 06 Dec 2013 17:07:12 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.0 MIME-Version: 1.0 To: "Ren, Qiaowei" , "Liu, Jinsong" , Paolo Bonzini CC: "kvm@vger.kernel.org" , "x86@kernel.org" , Xudong Hao , "qemu-devel@nongnu.org" , "linux-kernel@vger.kernel.org" , Ingo Molnar , Thomas Gleixner Subject: Re: [Qemu-devel] [PATCH v2 3/3] X86, mpx: Intel MPX xstate feature definition References: <1386375658-2191-1-git-send-email-qiaowei.ren@intel.com> <1386375658-2191-3-git-send-email-qiaowei.ren@intel.com> <52A20AD6.8080706@redhat.com> <52A242BE.3010701@zytor.com> <9E0BE1322F2F2246BD820DA9FC397ADE014A6115@SHSMSX102.ccr.corp.intel.com> In-Reply-To: <9E0BE1322F2F2246BD820DA9FC397ADE014A6115@SHSMSX102.ccr.corp.intel.com> X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.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