From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757318Ab0EGRrT (ORCPT ); Fri, 7 May 2010 13:47:19 -0400 Received: from mga10.intel.com ([192.55.52.92]:58103 "EHLO fmsmga102.fm.intel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756703Ab0EGRrQ (ORCPT ); Fri, 7 May 2010 13:47:16 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.52,349,1270450800"; d="scan'208";a="796418387" From: Jacob Pan To: Thomas Gleixner , "H. Peter Anvin" , Ingo Molnar , Alek Du , Arjan van de Ven , Feng Tang , LKML Cc: Jacob Pan , Jacob Pan Subject: [PATCH 1/8] x86: avoid check hlt if no timer interrupts Date: Fri, 7 May 2010 10:41:41 -0700 Message-Id: <1273254108-3234-2-git-send-email-jacob.jun.pan@linux.intel.com> X-Mailer: git-send-email 1.6.3.3 In-Reply-To: <1273254108-3234-1-git-send-email-jacob.jun.pan@linux.intel.com> References: <1273254108-3234-1-git-send-email-jacob.jun.pan@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jacob Pan check hlt requires external timer interrupt to wake up the cpu. for platforms equipped with only per cpu timers, we don't have external interrupts during check hlt. this patch checks such condition to avoid kernel hang at hlt. it also saves boot time in that hlt four times in the current code requires four ticks to break out of them. Signed-off-by: Jacob Pan Signed-off-by: Jacob Pan --- arch/x86/include/asm/bugs.h | 1 + arch/x86/kernel/cpu/bugs.c | 4 ++++ 2 files changed, 5 insertions(+), 0 deletions(-) diff --git a/arch/x86/include/asm/bugs.h b/arch/x86/include/asm/bugs.h index 08abf63..1e0cef8 100644 --- a/arch/x86/include/asm/bugs.h +++ b/arch/x86/include/asm/bugs.h @@ -2,6 +2,7 @@ #define _ASM_X86_BUGS_H extern void check_bugs(void); +extern struct clock_event_device *global_clock_event; #if defined(CONFIG_CPU_SUP_INTEL) && defined(CONFIG_X86_32) int ppro_with_ram_bug(void); diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 01a2652..c0d9688 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -90,6 +90,10 @@ static void __init check_hlt(void) return; printk(KERN_INFO "Checking 'hlt' instruction... "); + if (!global_clock_event) { + printk(KERN_CONT "no clockevent to wake up, skipped.\n"); + return; + } if (!boot_cpu_data.hlt_works_ok) { printk("disabled\n"); return; -- 1.6.3.3