From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757196Ab3BJWeD (ORCPT ); Sun, 10 Feb 2013 17:34:03 -0500 Received: from terminus.zytor.com ([198.137.202.10]:53771 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756902Ab3BJWeA (ORCPT ); Sun, 10 Feb 2013 17:34:00 -0500 User-Agent: K-9 Mail for Android In-Reply-To: <20130210222618.GA2573@pd.tnic> References: <1360483829-16349-1-git-send-email-lenb@kernel.org> <51181317.1080905@kernel.org> <20130210222618.GA2573@pd.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Subject: Re: [PATCH 2/2 v2] x86 idle: remove 32-bit-only "no-hlt" parameter, hlt_works_ok flag From: "H. Peter Anvin" Date: Sun, 10 Feb 2013 14:33:39 -0800 To: Borislav Petkov , Len Brown CC: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, Len Brown , x86@kernel.org Message-ID: <83c463ff-36e5-44b2-ac1e-73e2484def09@email.android.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Yes... safer that way. Borislav Petkov wrote: >On Sun, Feb 10, 2013 at 04:37:27PM -0500, Len Brown wrote: >> From: Len Brown >> >> Remove 32-bit x86 a cmdline param "no-hlt", >> and the cpuinfo_x86.hlt_works_ok that it sets. >> >> If a user wants to avoid HLT, then "idle=poll" >> is much more useful, as it avoids invocation of HLT >> in idle, while "no-hlt" failed to do so. >> >> Indeed, hlt_works_ok was consulted in only 3 places. >> >> First, in /proc/cpuinfo where "hlt_bug yes" >> would be printed if and only if the user booted >> the system with "no-hlt" -- as there was no other code >> to set that flag. >> >> Second, check_hlt() would not invoke halt() if "no-hlt" >> were on the cmdline. >> >> Third, it was consulted in stop_this_cpu(), which is invoked >> by native_machine_halt()/reboot_interrupt()/smp_stop_nmi_callback() >-- >> all cases where the machine is being shutdown/reset. >> The flag was not consulted in the more frequently invoked >> play_dead()/hlt_play_dead() used in processor offline and suspend. >> >> Since Linux-3.0 there has been a run-time notice upon "no-hlt" >invocations >> indicating that it would be removed in 2012. >> >> Signed-off-by: Len Brown >> Cc: x86@kernel.org >> --- >> v2: remove also check_hlt() > >[ … ] > >> diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c >> index 3286a92..e280253 100644 >> --- a/arch/x86/kernel/cpu/proc.c >> +++ b/arch/x86/kernel/cpu/proc.c >> @@ -28,7 +28,6 @@ static void show_cpuinfo_misc(struct seq_file *m, >struct cpuinfo_x86 *c) >> { >> seq_printf(m, >> "fdiv_bug\t: %s\n" >> - "hlt_bug\t\t: %s\n" > >Are we fine with changing /proc/cpuinfo output? We tend to consider it >an API to userspace, judging by past experience... -- Sent from my mobile phone. Please excuse brevity and lack of formatting.