From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752511Ab3ABCs6 (ORCPT ); Tue, 1 Jan 2013 21:48:58 -0500 Received: from smtp.nue.novell.com ([195.135.221.5]:43931 "EHLO smtp.nue.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752403Ab3ABCsz (ORCPT ); Tue, 1 Jan 2013 21:48:55 -0500 Subject: Re: [PATCH 1/3] rtc-efi: register rtc-efi device when EFI enabled From: joeyli To: "H. Peter Anvin" Cc: Matthew Garrett , "matt.fleming@intel.com" , "linux-kernel@vger.kernel.org" , "linux-efi@vger.kernel.org" , Thomas Gleixner , Ingo Molnar , Jan Beulich , Len Brown , Arjan van de Ven In-Reply-To: <50DE2EED.9030608@zytor.com> References: <1356712001-12198-1-git-send-email-jlee@suse.com> <3fa7337e-6bbc-4462-9704-2d8ac20a9cf2@email.android.com> <50DE03D8.9030902@zytor.com> <50DE2EED.9030608@zytor.com> Content-Type: text/plain; charset="UTF-8" Date: Wed, 02 Jan 2013 10:45:51 +0800 Message-ID: <1357094751.6113.253.camel@linux-s257.site> Mime-Version: 1.0 X-Mailer: Evolution 2.28.2 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi hpa, 於 五，2012-12-28 於 15:44 -0800，H. Peter Anvin 提到： > On 12/28/2012 12:49 PM, Matthew Garrett wrote: > > On Fri, 2012-12-28 at 12:40 -0800, H. Peter Anvin wrote: > > > >>> I suspect that what we *should* do looks like: > >>> > >>> 1. If ACPI exports a Time and Alarm Device (ACPI000E) the use it; > >>> 2. If ACPI exports an PC/AT device (PNP0B00/1/2) then use it(*); > >>> 3. If we have an EFI RTC use it; > >>> 4. Probe for a PC/AT RTC device. > > > > In terms of ordering, 3 should probably come before 2 - but that depends > > on us actually fixing the issues that are preventing some of these calls > > from working. As far as wallclock time goes, EFI is going to be > > available to us before we've parsed the DSDT to determine whether > > there's any ACPI devices, so we'll almost certainly end up having to use > > it at at least some point during boot. Otherwise, agreed. > > > > [Resending due to misconfigured tablet] > > 3 before 2 is exactly what is known to break on existing hardware (ASUS). I didn't find the EFI RTC problem on Asus from google. Could you please share what's the situation on ASUS hardware? Thanks a lot! Joey Lee > > If anything, we should move to using the EFI RTC as a very last resort, > i.e. 3 after 4. Ideally we should match Win8 behavior, but that would > require someone mocking up different ACPI and EFI functions in a > simulator and see how Win8 prioritizes things. > > -hpa > > -- > To unsubscribe from this list: send the line "unsubscribe linux-efi" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >