Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755651Ab0K2SIj (ORCPT ); Mon, 29 Nov 2010 13:08:39 -0500 Received: from mx1.redhat.com ([209.132.183.28]:28551 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755377Ab0K2SIh (ORCPT ); Mon, 29 Nov 2010 13:08:37 -0500 Message-ID: <4CF3EC1E.7050707@redhat.com> Date: Mon, 29 Nov 2010 08:08:30 -1000 From: Zachary Amsden User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.10) Gecko/20100621 Fedora/3.0.5-1.fc13 Thunderbird/3.0.5 MIME-Version: 1.0 To: Randy Dunlap CC: Avi Kivity , Glauber Costa , Stephen Rothwell , kvm@vger.kernel.org, linux-next@vger.kernel.org, LKML Subject: Re: linux-next: Tree for November 22 (kvm) References: <20101122134911.b7e106f9.sfr@canb.auug.org.au> <20101122132627.bd4e88ef.randy.dunlap@oracle.com> <20101129083324.6870d7da.randy.dunlap@oracle.com> <4CF3D637.6060204@redhat.com> <4CF3E733.8090809@redhat.com> <4CF3E870.4040308@oracle.com> In-Reply-To: <4CF3E870.4040308@oracle.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2374 Lines: 81 On 11/29/2010 07:52 AM, Randy Dunlap wrote: > On 11/29/10 09:47, Zachary Amsden wrote: > >> On 11/29/2010 06:35 AM, Avi Kivity wrote: >> >>> On 11/29/2010 06:33 PM, Randy Dunlap wrote: >>> >>>> On Mon, 22 Nov 2010 13:26:27 -0800 Randy Dunlap wrote: >>>> >>>> >>>>> On Mon, 22 Nov 2010 13:49:11 +1100 Stephen Rothwell wrote: >>>>> >>>>> >>>>>> Hi all, >>>>>> >>>>>> Changes since 20101119: >>>>>> >>>>> >>>>> kvm.c:(.init.text+0x11f49): undefined reference to >>>>> >>>> `kvm_register_clock' >>>> >>>>> when CONFIG_KVM_CLOCK is not enabled. >>>>> >>>> >>>> BUild error still present in linux-next-2010-NOV-29. >>>> >>>> >>> Glauber, Zach? >>> >>> >> I can only speculate this reference is being called from smpboot without >> CONFIG guarding? >> > Sorry, looks like I dropped the first line of the error messages: > > arch/x86/built-in.o: In function `kvm_smp_prepare_boot_cpu': > kvm.c:(.init.text+0xad38): undefined reference to `kvm_register_clock' > > from arch/x86/kernel/kvm.c: > > #ifdef CONFIG_SMP > static void __init kvm_smp_prepare_boot_cpu(void) > { > WARN_ON(kvm_register_clock("primary cpu clock")); > kvm_guest_cpu_init(); > native_smp_prepare_boot_cpu(); > } > > so it looks like you are correct... > Looks like this is the appropriate fix: #ifdef CONFIG_SMP static void __init kvm_smp_prepare_boot_cpu(void) { #ifdef CONFIG_KVM_CLOCK WARN_ON(kvm_register_clock("primary cpu clock")); #endif kvm_guest_cpu_init(); native_smp_prepare_boot_cpu(); } The SMP code is still buggy as well, wrt printk timing, in that it doesn't get called early enough, correct? Has anyone thought of a good solution to that problem? Basically the problem is CPU-1 will get CPU-0's per-cpu areas copied over, and these are not valid for CPU-1. If the clocksource is used on CPU-1 before kvm clock gets setup, it can go backwards, wreaking havoc, causing panic, etc. What is the best test to guard against this? Perhaps we should keep the CPU number in the per-cpu data and test against it? -- 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/