Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S270256AbTGWR2h (ORCPT ); Wed, 23 Jul 2003 13:28:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S270910AbTGWR2h (ORCPT ); Wed, 23 Jul 2003 13:28:37 -0400 Received: from twilight.cs.hut.fi ([130.233.40.5]:38119 "EHLO twilight.cs.hut.fi") by vger.kernel.org with ESMTP id S270256AbTGWR2g (ORCPT ); Wed, 23 Jul 2003 13:28:36 -0400 Date: Wed, 23 Jul 2003 20:43:25 +0300 From: Ville Herva To: Marcelo Tosatti , torvalds@osdl.org Cc: lkml , ak@suse.de Subject: [PATCH] NMI watchdog documentation Message-ID: <20030723174325.GL150921@niksula.cs.hut.fi> Mail-Followup-To: Ville Herva , Marcelo Tosatti , torvalds@osdl.org, lkml , ak@suse.de Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1990 Lines: 46 Documentation/nmi-watchdoc.txt doesn't actually tell what options need to be enabled in kernel config in order to use NMI watchdog. I for one found it confusing. I vaguely recall someone posted a similar patch some time ago, but it still doesn't seem to be present in 2.4 or 2.6-test. Andi: what about x86-64 - does it have something similar that should be mentioned? -- v -- v@iki.fi --- linux/Documentation/nmi_watchdog.txt Tue Sep 18 09:03:09 2001 +++ linux~/Documentation/nmi_watchdog.txt Wed Jul 23 20:25:42 2003 @@ -8,9 +8,20 @@ which get executed even if the system is otherwise locked up hard). This can be used to debug hard kernel lockups. By executing periodic NMI interrupts, the kernel can monitor whether any CPU has locked up, -and print out debugging messages if so. You must enable the NMI -watchdog at boot time with the 'nmi_watchdog=n' boot parameter. Eg. -the relevant lilo.conf entry: +and print out debugging messages if so. + +In order to use the NMI watchdoc, you need to have APIC support in your +kernel. For SMP kernels, APIC support gets compiled in automatically. For +UP, enable either CONFIG_X86_UP_APIC (Processor type and features -> Local +APIC support on uniprocessors) or CONFIG_X86_UP_IOAPIC (Processor type and +features -> IO-APIC support on uniprocessors) in your kernel config. +CONFIG_X86_UP_APIC is for uniprocessor machines without an IO-APIC. +CONFIG_X86_UP_IOAPIC is for uniprocessor with an IO-APIC. [Note: certain +kernel debugging options, such as Kernel Stack Meter or Kernel Tracer, +may implicitly disable the NMI watchdog.] + +To actually enable the NMI watchdog, use the 'nmi_watchdog=N' boot +parameter. Eg. the relevant lilo.conf entry: append="nmi_watchdog=1" - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/