From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757620AbaLJTl7 (ORCPT ); Wed, 10 Dec 2014 14:41:59 -0500 Received: from mga11.intel.com ([192.55.52.93]:29296 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755088AbaLJTl6 (ORCPT ); Wed, 10 Dec 2014 14:41:58 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.97,862,1389772800"; d="scan'208";a="427466627" Message-ID: <5488A203.7000600@linux.intel.com> Date: Wed, 10 Dec 2014 11:41:55 -0800 From: Dave Hansen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 MIME-Version: 1.0 To: Linus Torvalds , Thomas Gleixner CC: LKML , Andrew Morton , the arch/x86 maintainers Subject: Re: [GIT pull] x86 mpx support for 3.19 References: In-Reply-To: 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 12/10/2014 11:05 AM, Linus Torvalds wrote: > Why would I want to enable this in my kernel when there are no actual > CPU's out yet that support it? And even when there are, why would I do > it if the CPU I have doesn't support it? For folks that build their own kernels and know what CPU they have, you'd never want to enable it other than compile testing (or maybe some basic runtime testing to make sure we didn't mess up the #BR code on CPUs without the feature). But, this is the kind of option that we want to be *sure* is enabled unless folks know exactly what they are doing, so we should probably hide it behind CONFIG_EXPERT as well, just as SMEP is. We might be getting to the point where we need to bury all these Intel-specific options somewhere, but that's a patch for another day. Patch is attached to convert it over to this: config X86_INTEL_MPX prompt "Intel MPX (Memory Protection Extensions)" if EXPERT def_bool y depends on CPU_SUP_INTEL ---help--- MPX provides hardware features that can be used in conjunction with compiler-instrumented code to check memory references. It is designed to detect buffer overflow or underflow bugs. Enabling this option will make the kernel larger and slightly increase the size of some data structures. If unsure, say Y.