On Thu, Sep 12, 2013 at 11:42:17AM +0300, Michael S. Tsirkin wrote: > On Thu, Sep 12, 2013 at 11:23:46AM +0300, Gal Hammer wrote: > > Hi, > > > > I've notice that the virtio-serial Windows' driver doesn't use MSI-X > > vectors when running using upstream qemu or > > qemu-kvm-1.2.2-13.fc18.x86_64. The same VM works with MSI-X when > > using qemu-kvm-0.12.1.2-2.355.el6.x86_64. > > > > From what I saw, Windows is trying to enable MSI-X by writing a 2 > > bytes value to device's PCI-config address 66h. > > > > So when everything works well the flow goes like this: > > > > pci_default_write_config value: 8000 len: 2 > > pci_default_write_config value: 1 len: 2 > > msix_enabled 0 (67) > > pci_default_write_config value: e107 len: 2 > > pci_default_write_config value: 1 len: 2 > > msix_enabled 0 (67) > > pci_default_write_config value: 8001 len: 2 > > msix_enabled 1 (67) > > > > But on upstream it goes: > > > > pci_default_write_config addr: 66 value: 8000 size: 2 > > pci_default_write_config addr: 66 value: 1 size: 2 > > msix_enabled 0 (67) > > pci_default_write_config addr: 66 value: e307 size: 2 (NOTE: Value > > is diffrent!). > > pci_default_write_config addr: 66 value: 1 size: 2 > > msix_enabled 0 (67) > > > > (NOTE: Missing the write of 8001). > > > > My qemu's command line: > > > > ---< snip >--- > > > > /usr/bin/qemu-kvm -m 1G -smp 2 -enable-kvm -usb -device usb-tablet \ > > -device > > ide-drive,drive=drive-virtio0-0-0,id=virtio0-0-0,bootindex=1 \ > > -drive > > file=win7_32_viorng.qcow2,if=none,id=drive-virtio0-0-0,format=qcow2,werror=stop,rerror=stop,cache=none > > \ > > -monitor stdio \ > > -vga qxl -spice id=on,disable-ticketing,port=5903 \ > > -device virtio-serial-pci,id=virtio-serial0,vectors=2 \ > > -chardev spicevmc,id=spicechannel0,name=vdagent > > > > ---< snip >--- > > > > Thanks, > > > > Gal. > > > So it's a known change from qemu-kvm to qemu. > With qemu-kvm the default cpu was kvm64. > With qemu the default cpu is qemu64 even if you use -enable-kvm. > > Not an issue for libvirt as that specifies -cpu, > but will be an issue for command-line users. > > Maybe we should change the default for new machine types and when > -enable-kvm is specified?
What about simply making qemu64 as good as kvm64 (on newer machine-types)? What exactly is missing on qemu64 that causes the above problem? -- Eduardo
