Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753415AbcJTTNu (ORCPT ); Thu, 20 Oct 2016 15:13:50 -0400 Received: from Galois.linutronix.de ([146.0.238.70]:49443 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752409AbcJTTNt (ORCPT ); Thu, 20 Oct 2016 15:13:49 -0400 Date: Thu, 20 Oct 2016 21:10:00 +0200 (CEST) From: Thomas Gleixner To: Grzegorz Andrejczuk cc: mingo@redhat.com, hpa@zytor.com, x86@kernel.org, bp@suse.de, dave.hansen@linux.intel.com, linux-kernel@vger.kernel.org, lukasz.daniluk@intel.com, james.h.cownie@intel.com, jacob.jun.pan@intel.com Subject: Re: [PATCH v4 2/4] x86/phi: Add enabling of the R3MWAIT during boot In-Reply-To: <1476784971-23872-3-git-send-email-grzegorz.andrejczuk@intel.com> Message-ID: References: <1476784971-23872-1-git-send-email-grzegorz.andrejczuk@intel.com> <1476784971-23872-3-git-send-email-grzegorz.andrejczuk@intel.com> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 554 Lines: 17 On Tue, 18 Oct 2016, Grzegorz Andrejczuk wrote: > +static void probe_xeon_phi_r3mwait(struct cpuinfo_x86 *c) > +{ > + if (phi_r3mwait_disabled) > + return; So you return when the command line option to disable the feature was given. That's not really a good choice if the feature is already enabled due to BIOS featuritis. This can also happen when you kexec from a enabled kernel into one which has the command line option set. You really should make sure that the command line option results in disabling the feature no matter what. Thanks, tglx