First look in /var/log/libvirt/qemu/<domainname>.log and see which qemu

binary is being executed by libvirt - it may not be the one you've built.

It looks correct... I pulled out the driver tag from my config and fired it up. Here is the full command line for it: LC_ALL=C PATH=/sbin:/usr/sbin:/bin:/usr/bin:/usr/local/sbin:/usr/local/bin QEMU_AUDIO_DRV=none /usr/local/bin/qemu-system-x86_64 -S -M pc-0.14 -enable-kvm -m 4096 -smp 7,sockets=7,cores=1,threads=1 -name web101 -uuid bda63821-ccc4-6607-67c0-db6712526cbd -nodefconfig -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/web101.monitor,server,nowait -mon chardev=charmonitor,id=monitor,mode=readline -rtc base=utc -boot c -drive file=/var/lib/libvirt/images/web101.img,if=none,id=drive-virtio-disk0,format=raw,cache=writethrough -device virtio-blk-pci,bus=pci.0,addr=0x5,drive=drive-virtio-disk0,id=virtio-disk0 -drive file=/home/httpd.img,if=none,id=drive-virtio-disk1,format=raw,cache=writethrough -device virtio-blk-pci,bus=pci.0,addr=0x7,drive=drive-virtio-disk1,id=virtio-disk1 -drive if=none,media=cdrom,id=drive-ide0-1-0,readonly=on,format=raw -device ide-drive,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0 -fsdev local,security_model=passthrough,id=fsdev-fs0,path=/home/httpd -device virtio-9p-pci,id=fs0,fsdev=fsdev-fs0,mount_tag=/home/httpd,bus=pci.0,addr=0x8 -netdev tap,fd=15,id=hostnet0 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:6f:51:43,bus=pci.0,addr=0x3 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -usb -device usb-tablet,id=input0 -vnc 127.0.0.1:0 -vga cirrus -device AC97,id=sound0,bus=pci.0,addr=0x4 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x6

Then, run "qemu-kvm --help" (replacing "qemu-kvm" with the path to the binary that libvirt is executing, found in the previous paragraph), and search through that output for the string ",vhost=" - if it's not there, then your qemu doesn't support vhost-net.

This also looks correct. Is it wrong that my qemu compilation didn't create a binary named "qemu-kvm"? (Even though it said "KVM support yes" on the configure output?) # /usr/local/bin/qemu-system-x86_64 --help |grep vhost -net tap[,vlan=n][,name=str][,fd=h][,ifname=name][,script=file][,downscript=dfile][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off][,vhostfd=h][,vhostforce=on|off] use vhost=on to enable experimental in kernel accelerator use vhostforce=on to force vhost on for non-MSIX virtio guests use 'vhostfd=h' to connect to an already opened vhost net device

If that string *is* there, then we need to do some more investigating, starting with you sending the output of "qemu-kvm --help".

Here's the full output for you. # /usr/local/bin/qemu-system-x86_64 --help QEMU emulator version 0.14.1, Copyright (c) 2003-2008 Fabrice Bellard usage: qemu [options] [disk_image] 'disk_image' is a raw hard disk image for IDE hard disk 0 Standard options: -h or -help display this help and exit -version display version information and exit -M machine select emulated machine (-M ? for list) -cpu cpu select CPU (-cpu ? for list) -smp n[,maxcpus=cpus][,cores=cores][,threads=threads][,sockets=sockets] set the number of CPUs to 'n' [default=1] maxcpus= maximum number of total cpus, including offline CPUs for hotplug, etc cores= number of CPU cores on one socket threads= number of threads on one CPU core sockets= number of discrete sockets in the system -numa node[,mem=size][,cpus=cpu[-cpu]][,nodeid=node] -fda/-fdb file use 'file' as floppy disk 0/1 image -hda/-hdb file use 'file' as IDE hard disk 0/1 image -hdc/-hdd file use 'file' as IDE hard disk 2/3 image -cdrom file use 'file' as IDE cdrom image (cdrom is ide1 master) -drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i] [,cyls=c,heads=h,secs=s[,trans=t]][,snapshot=on|off] [,cache=writethrough|writeback|none|unsafe][,format=f] [,serial=s][,addr=A][,id=name][,aio=threads|native] [,readonly=on|off] use 'file' as a drive image -set group.id.arg=value set <arg> parameter for item <id> of type <group> i.e. -set drive.$id.file=/path/to/image -global driver.property=value set a global default for a driver property -mtdblock file use 'file' as on-board Flash memory image -sd file use 'file' as SecureDigital card image -pflash file use 'file' as a parallel flash image -boot [order=drives][,once=drives][,menu=on|off] 'drives': floppy (a), hard disk (c), CD-ROM (d), network (n) -snapshot write to temporary files instead of disk image files -m megs set virtual RAM size to megs MB [default=128] -mem-path FILE provide backing storage for guest RAM -mem-prealloc preallocate guest memory (use with -mem-path) -k language use keyboard layout (for example 'fr' for French) -audio-help print list of audio drivers and their options -soundhw c1,... enable audio support and only specified sound cards (comma separated list) use -soundhw ? to get the list of supported cards use -soundhw all to enable all of them -usb enable the USB driver (will be the default soon) -usbdevice name add the host or guest USB device 'name' -device driver[,prop[=value][,...]] add device (based on driver) prop=value,... sets driver properties use -device ? to print all possible drivers use -device driver,? to print all possible properties File system options: -fsdev local,id=id,path=path,security_model=[mapped|passthrough|none] Virtual File system pass-through options: -virtfs local,path=path,mount_tag=tag,security_model=[mapped|passthrough|none] -name string1[,process=string2] set the name of the guest string1 sets the window title and string2 the process name (on Linux) -uuid %08x-%04x-%04x-%04x-%012x specify machine UUID Display options: -nographic disable graphical output and redirect serial I/Os to console -spice <args> enable spice -portrait rotate graphical output 90 deg left (only PXA LCD) -vga [std|cirrus|vmware|qxl|xenfb|none] select video card type -full-screen start in full screen -g WxH[xDEPTH] Set the initial graphical resolution and depth -vnc display start a VNC server on display i386 target only: -win2k-hack use it when installing Windows 2000 to avoid a disk full bug -no-fd-bootchk disable boot signature checking for floppy disks -no-acpi disable ACPI -no-hpet disable HPET -balloon none disable balloon device -balloon virtio[,addr=str] enable virtio balloon device (default) -acpitable [sig=str][,rev=n][,oem_id=str][,oem_table_id=str][,oem_rev=n][,asl_compiler_id=str][,asl_compiler_rev=n][,data=file1[:file2]...] ACPI table description -smbios file=binary load SMBIOS entry from binary file -smbios type=0[,vendor=str][,version=str][,date=str][,release=%d.%d] specify SMBIOS type 0 fields -smbios type=1[,manufacturer=str][,product=str][,version=str][,serial=str] [,uuid=uuid][,sku=str][,family=str] specify SMBIOS type 1 fields Network options: -net nic[,vlan=n][,macaddr=mac][,model=type][,name=str][,addr=str][,vectors=v] create a new Network Interface Card and connect it to VLAN 'n' -net user[,vlan=n][,name=str][,net=addr[/mask]][,host=addr][,restrict=y|n] [,hostname=host][,dhcpstart=addr][,dns=addr][,tftp=dir][,bootfile=f] [,hostfwd=rule][,guestfwd=rule][,smb=dir[,smbserver=addr]] connect the user mode network stack to VLAN 'n', configure its DHCP server and enabled optional services -net tap[,vlan=n][,name=str][,fd=h][,ifname=name][,script=file][,downscript=dfile][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off][,vhostfd=h][,vhostforce=on|off] connect the host TAP network interface to VLAN 'n' and use the network scripts 'file' (default=/etc/qemu-ifup) and 'dfile' (default=/etc/qemu-ifdown) use '[down]script=no' to disable script execution use 'fd=h' to connect to an already opened TAP interface use 'sndbuf=nbytes' to limit the size of the send buffer (the default is disabled 'sndbuf=0' to enable flow control set 'sndbuf=1048576') use vnet_hdr=off to avoid enabling the IFF_VNET_HDR tap flag use vnet_hdr=on to make the lack of IFF_VNET_HDR support an error condition use vhost=on to enable experimental in kernel accelerator (only has effect for virtio guests which use MSIX) use vhostforce=on to force vhost on for non-MSIX virtio guests use 'vhostfd=h' to connect to an already opened vhost net device -net socket[,vlan=n][,name=str][,fd=h][,listen=[host]:port][,connect=host:port] connect the vlan 'n' to another VLAN using a socket connection -net socket[,vlan=n][,name=str][,fd=h][,mcast=maddr:port[,localaddr=addr]] connect the vlan 'n' to multicast maddr and port use 'localaddr=addr' to specify the host address to send packets from -net dump[,vlan=n][,file=f][,len=n] dump traffic on vlan 'n' to file 'f' (max n bytes per packet) -net none use it alone to have zero network devices. If no -net option is provided, the default is '-net nic -net user' -netdev [user|tap|socket],id=str[,option][,option][,...] Character device options: -chardev null,id=id[,mux=on|off] -chardev socket,id=id[,host=host],port=host[,to=to][,ipv4][,ipv6][,nodelay] [,server][,nowait][,telnet][,mux=on|off] (tcp) -chardev socket,id=id,path=path[,server][,nowait][,telnet],[mux=on|off] (unix) -chardev udp,id=id[,host=host],port=port[,localaddr=localaddr] [,localport=localport][,ipv4][,ipv6][,mux=on|off] -chardev msmouse,id=id[,mux=on|off] -chardev vc,id=id[[,width=width][,height=height]][[,cols=cols][,rows=rows]] [,mux=on|off] -chardev file,id=id,path=path[,mux=on|off] -chardev pipe,id=id,path=path[,mux=on|off] -chardev pty,id=id[,mux=on|off] -chardev stdio,id=id[,mux=on|off][,signal=on|off] -chardev tty,id=id,path=path[,mux=on|off] -chardev parport,id=id,path=path[,mux=on|off] Bluetooth(R) options: -bt hci,null dumb bluetooth HCI - doesn't respond to commands -bt hci,host[:id] use host's HCI with the given name -bt hci[,vlan=n] emulate a standard HCI in virtual scatternet 'n' -bt vhci[,vlan=n] add host computer to virtual scatternet 'n' using VHCI -bt device:dev[,vlan=n] emulate a bluetooth device 'dev' in scatternet 'n' Linux/Multiboot boot specific: -kernel bzImage use 'bzImage' as kernel image -append cmdline use 'cmdline' as kernel command line -initrd file use 'file' as initial ram disk Debug/Expert options: -serial dev redirect the serial port to char device 'dev' -parallel dev redirect the parallel port to char device 'dev' -monitor dev redirect the monitor to char device 'dev' -qmp dev like -monitor but opens in 'control' mode -mon chardev=[name][,mode=readline|control][,default] -debugcon dev redirect the debug console to char device 'dev' -pidfile file write PID to 'file' -singlestep always run in singlestep mode -S freeze CPU at startup (use 'c' to start execution) -gdb dev wait for gdb connection on 'dev' -s shorthand for -gdb tcp::1234 -d item1,... output log to /tmp/qemu.log (use -d ? for a list of log items) -hdachs c,h,s[,t] force hard disk 0 physical geometry and the optional BIOS translation (t=none or lba) (usually qemu can guess them) -L path set the directory for the BIOS, VGA BIOS and keymaps -bios file set the filename for the BIOS -enable-kvm enable KVM full virtualization support -xen-domid id specify xen guest domain id -xen-create create domain using xen hypercalls, bypassing xend warning: should not be used when xend is in use -xen-attach attach to existing xen domain xend will use this when starting qemu -no-reboot exit instead of rebooting -no-shutdown stop before shutdown -loadvm [tag|id] start right away with a saved state (loadvm in monitor) -daemonize daemonize QEMU after initializing -option-rom rom load a file, rom, into the option ROM space -clock force the use of the given methods for timer alarm. To see what timers are available use -clock ? -rtc [base=utc|localtime|date][,clock=host|vm][,driftfix=none|slew] set the RTC base and clock, enable drift fix for clock ticks (x86 only) -icount [N|auto] enable virtual instruction counter with 2^N clock ticks per instruction -watchdog i6300esb|ib700 enable virtual hardware watchdog [default=none] -watchdog-action reset|shutdown|poweroff|pause|debug|none action when watchdog fires [default=reset] -echr chr set terminal escape character instead of ctrl-a -virtioconsole c set virtio console -show-cursor show cursor -tb-size n set TB size -incoming p prepare for incoming migration, listen on port p -nodefaults don't create default devices -chroot dir chroot to dir just before starting the VM -runas user change to user id user just before starting the VM -prom-env variable=value set OpenBIOS nvram variables -semihosting semihosting mode -old-param old param mode -readconfig <file> -writeconfig <file> read/write config file -nodefconfig do not load default config files at startup During emulation, the following keys are useful: ctrl-alt-f toggle full screen ctrl-alt-n switch to virtual console 'n' ctrl-alt toggle mouse and keyboard grab When using -nographic, press 'ctrl-a h' to get some help. Thanks for the help! --Cal