From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751021Ab3JRG3N (ORCPT ); Fri, 18 Oct 2013 02:29:13 -0400 Received: from mail-ea0-f169.google.com ([209.85.215.169]:53882 "EHLO mail-ea0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750826Ab3JRG3L (ORCPT ); Fri, 18 Oct 2013 02:29:11 -0400 Date: Fri, 18 Oct 2013 08:29:08 +0200 From: Ingo Molnar To: Jan Beulich , John Stultz Cc: mingo@elte.hu, tglx@linutronix.de, hpa@zytor.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86: honor ACPI FADT flag indicating absence of a CMOS RTC Message-ID: <20131018062908.GD14264@gmail.com> References: <525E969E02000078000FB710@nat28.tlf.novell.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <525E969E02000078000FB710@nat28.tlf.novell.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Jan Beulich wrote: > We shouldn't be creating a corresponding platform device in that case. There's a sad lack of context in the changelog, how was it found, does this address any problem/bug observed in practice, etc? > Signed-off-by: Jan Beulich > > --- > arch/x86/kernel/rtc.c | 5 +++++ > 1 file changed, 5 insertions(+) > > --- 3.12-rc5/arch/x86/kernel/rtc.c > +++ 3.12-rc5-x86-ACPI-no-RTC/arch/x86/kernel/rtc.c > @@ -192,6 +192,11 @@ static __init int add_rtc_cmos(void) > if (mrst_identify_cpu()) > return -ENODEV; > > +#ifdef CONFIG_ACPI > + if (acpi_gbl_FADT.boot_flags & ACPI_FADT_NO_CMOS_RTC) > + return -ENODEV; > +#endif It might also be prudent to emit a KERN_INFO line telling that we don't create the device - so that people who suddenly see unexpected breakage or change in behavior have a chance to see what we've done? Thanks, Ingo