From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754210Ab3EKO4W (ORCPT ); Sat, 11 May 2013 10:56:22 -0400 Received: from terminus.zytor.com ([198.137.202.10]:47549 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754045Ab3EKO4U (ORCPT ); Sat, 11 May 2013 10:56:20 -0400 User-Agent: K-9 Mail for Android In-Reply-To: References: <1367476850.5660.2.camel@nexus>, MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: RE: [tip:x86/urgent] x86-64, init: Do not set NX bits on non-NX capable hardware From: "H. Peter Anvin" Date: Sat, 11 May 2013 07:55:58 -0700 To: Yuhong Bao , "mingo@kernel.org" , "linux-tip-commits@vger.kernel.org" CC: "linux-kernel@vger.kernel.org" , "fernando@oss.ntt.co.jp" , "tglx@linutronix.de" , "hpa@linux.intel.com" Message-ID: <6d735c4c-ee73-4f42-baa9-1791bae17ed6@email.android.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Yes... But both apply. Yuhong Bao wrote: >(resending as plaintext) >> During early init, we would incorrectly set the NX bit even if the NX >> feature was not supported. Instead, only set this bit if NX is >> actually available and enabled. We already do very early detection >of >> the NX bit to enable it in EFER, this simply extends this detection >to >> the early page table mask. >AFAIK the only production x86-64 processor that don't support NX that I >know of is the original Nocona D0 stepping. >Must more common are the problem of BIOSes disabling the NX feature. > > >Yuhong Bao -- Sent from my mobile phone. Please excuse brevity and lack of formatting.