Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753263AbaA0Bu6 (ORCPT ); Sun, 26 Jan 2014 20:50:58 -0500 Received: from terminus.zytor.com ([198.137.202.10]:40612 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753125AbaA0Bu5 (ORCPT ); Sun, 26 Jan 2014 20:50:57 -0500 Message-ID: <52E5BB66.8060104@zytor.com> Date: Sun, 26 Jan 2014 17:50:30 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: Ingo Molnar , Ren Qiaowei CC: Thomas Gleixner , Ingo Molnar , x86@kernel.org, linux-kernel@vger.kernel.org, Peter Zijlstra Subject: Re: [PATCH v3 3/4] x86, mpx: add prctl commands PR_MPX_INIT, PR_MPX_RELEASE References: <1390727338-20487-1-git-send-email-qiaowei.ren@intel.com> <1390727338-20487-4-git-send-email-qiaowei.ren@intel.com> <20140126082201.GB28831@gmail.com> <52E4C5F2.8070707@intel.com> <20140126083942.GB29339@gmail.com> In-Reply-To: <20140126083942.GB29339@gmail.com> X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/26/2014 12:39 AM, Ingo Molnar wrote: >> >> It will be only once per startup. > > In that case it would be more efficient to make this part of the > binary execution environment so that exec() sets it up automatically, > not a separate prctl() syscall. > This is not necessarily possible, and in particular it might need to be deferred until the MPX runtime has initialized. What isn't clear to me is if these syscalls are needed at all, or if it would be better to just let the MPX runtile set BNDSTATUS and BNDCFGU directly in userspace. The kernel cannot rely on them staying consistent across userspace anyway. Now, it might be beneficial for the kernel to have them anyway. It's a bit of a tough call. -hpa -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/