From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757769Ab3DXTpN (ORCPT ); Wed, 24 Apr 2013 15:45:13 -0400 Received: from mail-we0-f172.google.com ([74.125.82.172]:33370 "EHLO mail-we0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757465Ab3DXTpJ (ORCPT ); Wed, 24 Apr 2013 15:45:09 -0400 MIME-Version: 1.0 In-Reply-To: <1366828376-18124-1-git-send-email-john.stultz@linaro.org> References: <1366828376-18124-1-git-send-email-john.stultz@linaro.org> From: Kay Sievers Date: Wed, 24 Apr 2013 21:44:47 +0200 Message-ID: Subject: Re: [PATCH] time: Revert ALWAYS_USE_PERSISTENT_CLOCK compile time optimizaitons To: John Stultz Cc: lkml , stable , Feng Tang , Jason Gunthorpe , Thomas Gleixner Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 24, 2013 at 8:32 PM, John Stultz wrote: > Kay Sievers noted that the ALWAYS_USE_PERSISTENT_CLOCK config, > which enables some minor compile time optimization to avoid > uncessary code in mostly the suspend/resume path could cause > problems for userland. > > In particular, the dependency for RTC_HCTOSYS on > !ALWAYS_USE_PERSISTENT_CLOCK, which avoids setting the time > twice and simplifies suspend/resume, has the side effect > of causing the /sys/class/rtc/rtcN/hctosys flag to always be > zero, and this flag is commonly used by udev to setup the > /dev/rtc symlink to /dev/rtcN, which can cause pain for > older applications. An alternative to reverting this could be to set that flag unconditionally on the rtc that matches the persistent clock the kernel uses internally? I mean regardless of the pretty weird config option CONFIG_RTC_HCTOSYS_DEVICE, which internally just does a strcmp() with the given device name when the flag is queried. :) Can't we just have the same interface and your original optimization on x86, even without CONFIG_RTC_HCTOSYS_DEVICE enabled at all? Kay