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, <OK>. > 2) manually turning on X86_IO_APIC, <OK>. > 3) with 3.16 kernel, disabling PCI_MSI, <OK> > 4) with 3.16 kernel, disabling PCI_MSI, enabling X86_UP_APIC, <fail> > > 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
