From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752164AbaKQRC2 (ORCPT ); Mon, 17 Nov 2014 12:02:28 -0500 Received: from bh-25.webhostbox.net ([208.91.199.152]:58926 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751359AbaKQRCZ (ORCPT ); Mon, 17 Nov 2014 12:02:25 -0500 Date: Mon, 17 Nov 2014 09:02:15 -0800 From: Guenter Roeck To: Jiang Liu Cc: Stephen Rothwell , linux-next@vger.kernel.org, linux-kernel@vger.kernel.org, Thomas Gleixner Subject: Re: linux-next: Tree for Nov 14 Message-ID: <20141117170215.GC28915@roeck-us.net> References: <20141114192738.08e744cc@canb.auug.org.au> <20141115211922.GA2347@roeck-us.net> <54680D0A.7070900@linux.intel.com> <5468185D.5020400@roeck-us.net> <546983B1.6060105@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <546983B1.6060105@linux.intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Authenticated_sender: guenter@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-CTCH-PVer: 0000001 X-CTCH-Spam: Unknown X-CTCH-VOD: Unknown X-CTCH-Flags: 0 X-CTCH-RefID: str=0001.0A020203.546A2A21.003C,ss=1,re=0.001,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0 X-CTCH-Score: 0.001 X-CTCH-ScoreCust: 0.000 X-CTCH-Rules: C_4847, X-CTCH-SenderID: linux@roeck-us.net X-CTCH-SenderID-Flags: 0 X-CTCH-SenderID-TotalMessages: 4 X-CTCH-SenderID-TotalSpam: 0 X-CTCH-SenderID-TotalSuspected: 0 X-CTCH-SenderID-TotalConfirmed: 0 X-CTCH-SenderID-TotalBulk: 0 X-CTCH-SenderID-TotalVirus: 0 X-CTCH-SenderID-TotalRecipients: 0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: mailgid no entry from get_relayhosts_entry X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 17, 2014 at 01:12:17PM +0800, Jiang Liu wrote: > On 2014/11/16 11:22, Guenter Roeck wrote: > > On 11/15/2014 06:33 PM, Jiang Liu wrote: > >> Hi Guenter, > >> Could you please help to provide the config file and > >> error messages? > > > > Config file: > > https://github.com/groeck/linux-build-test/blob/master/rootfs/x86/qemu_x86_pc_nosmp_defconfig > > > > > > Error log: > > http://server.roeck-us.net:8010/builders/qemu-x86-next/builds/44/steps/qemubuildcommand/logs/stdio > > > > > > You can find the root file system used for the test as well as the test > > script at > > https://github.com/groeck/linux-build-test/tree/master/rootfs/x86 > > > > There isn't really an error message, though - the boot stalls until the > > controlling daemon > > kills the qemu session. > Hi Guenter, > With the test suite at > https://github.com/groeck/linux-build-test/tree/master/rootfs/x86 > and configuration file qemu_x86_pc_nosmp_defconfig, I have > following findings: > 1) disabling PCI_MSI, . > 2) manually turning on X86_IO_APIC, . > 3) with 3.16 kernel, disabling PCI_MSI, > 4) with 3.16 kernel, disabling PCI_MSI, enabling X86_UP_APIC, > > So the root cause is that KVM doesn't support the configuration with > LOCAL_APIC enabled but IO_APIC disabled, though this configuration > works with bare-metal machines. > There are two possible solutions here: > 1) ALways enalbe IO_APIC if KVM is enabled. > 2) Enhance KVM to support LOCAL_APIC when IOAPIC is disabled. > > But I'm not familiar with KVM and don't know how to achieve solution 2. > Any suggestions? I don't understand KVM well enough either. For my part I don't understand why APIC configuration in the kernel differs between the SMP and the non-SMP case (ie why X86_IO_APIC is enabled for smp but not for non-smp). After all, the hardware does not change. On the other side I don't have to understand it ;-). I "solved" the problem in my test scripts by disabling PCI_MSI for the x86/non-smp test. That doesn't really solve anything, but there is only so much I can do. Thanks, Guenter