From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759421AbbCDUVd (ORCPT ); Wed, 4 Mar 2015 15:21:33 -0500 Received: from mga02.intel.com ([134.134.136.20]:21184 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759327AbbCDUVa (ORCPT ); Wed, 4 Mar 2015 15:21:30 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.09,689,1418112000"; d="scan'208";a="462565912" Message-ID: <1425500461.3838.140.camel@linux.intel.com> Subject: Re: [PATCH] x86: Bypass legacy PIC and PIT on ACPI hardware reduced platform From: Alan Cox To: Borislav Petkov Cc: "Rafael J. Wysocki" , Arjan van de Ven , Ingo Molnar , "Li, Aubrey" , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , Len.Brown@intel.com, x86@kernel.org, LKML Date: Wed, 04 Mar 2015 20:21:01 +0000 In-Reply-To: <20150304140555.GG3516@pd.tnic> References: <54F67ACC.3010500@linux.intel.com> <54F6C59C.706@linux.intel.com> <20150304095011.GH3233@pd.tnic> <8773039.WD3UIoUtJl@vostro.rjw.lan> <20150304140555.GG3516@pd.tnic> Organization: Intel Corporation Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.9 (3.12.9-1.fc21) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2015-03-04 at 15:05 +0100, Borislav Petkov wrote: > On Wed, Mar 04, 2015 at 03:16:07PM +0100, Rafael J. Wysocki wrote: > > Sort of. What we need is a "do not touch PIC/PIT" bit for the code that > > tries to fall back to them in some cases (which may appear to work if > > the hardware is physically there, but it may confuse the platform). > > Can "some cases" detection be nicely put into a x86_platform > platform-specific method? In some cases they don't belong in x86, ACPI is also used for ARM64. However if ( has_8259_pic() ) is trivally 0, 1 or some platform or acpi provided method.