Bug 505106

I found an issue where the libvirt-generated qemu command line uses the
'script' parameter incorrectly in combination with -net.  It turns out it
does not lead to a failure today but could later if qemu behaviour changes.

The F11 virtualization host has its primary interface configured as a bridge.
When using virt-manager to set up the guest, therefore, I made use of the host
bridged interface and that is reflected in the qemu-kvm command line.

This is the command line that ended up being used:

/usr/bin/qemu-kvm -S -M pc -m 2048 -smp 8 -name f11-test -uuid 41ed0f4f-cb0d-7d6a-ffb6-b33106d519ef -monitor pty -pidfile /var/run/libvirt/qemu//f11-test.pid -boot c -drive file=/var/lib/libvirt/images/f11-test-1.img,if=virtio,index=0,boot=on -drive file=/dev/sdb,if=virtio,index=1 -net nic,macaddr=54:52:00:4a:ee:0e,vlan=0,model=virtio -net tap,fd=21,script=,vlan=0,ifname=vnet0 -serial pty -parallel none -usb -usbdevice tablet -vnc 127.0.0.1:0 -soundhw es1370

The important part with respect to this bug is:
-net tap,fd=21,script=,vlan=0,ifname=vnet0

As far as I can tell in the documentation and my own by-hand runs of this,
'script=' is not correct.  It should be 'script=no'

It turns out that this doesn't generate an error.  When I was trying my own
runs of qemu-kvm based on the libvirt-generated command line, I added my own
tap interface with tunctl and tried to point qemu-kvm at that.  Because I did
it this way, I did not have the 'fd=x' piece in there.  In that scenario,
qemu-kvm refused to start with this syntax error:

/etc/qemu-ifup: could not launch network script
Could not initialize device 'tap'

This was the FAILING attempted command line:
/usr/bin/qemu-kvm -M pc -m 2048 -smp 8 -name f11-test -uui41ed0f4f-cb0d-7d6a-ffb6-b33106d519ef -pidfile /var/run/libvirt/qemu//f11-test.pid -boot c -drive file=/var/lib/libvirt/images/f11-test-1.img,if=virtio,index=0,boot=on -drive file=/dev/sdb,if=virtio,index=1,cache=none -net nic,macaddr=54:52:00:4a:ee:0e,vlan=0,model=virtio -net tap,script=,vlan=0,ifname=tap0 -parallel none -usb -usbdevice tablet -soundhw es1370

And this is the important part with respect to this bug:
-net tap,script=,vlan=0,ifname=tap0

The final command line I used was this, and it worked (replacing the script=
with script=no):

/usr/bin/qemu-kvm -M pc -m 2048 -smp 8 -name f11-test -uuid 41ed0f4f-cb0d-7d6a-ffb6-b33106d519ef -pidfile /var/run/libvirt/qemu//f11-test.pid -boot c -drive file=/var/lib/libvirt/images/f11-test-1.img,if=virtio,index=0,boot=on -drive file=/dev/sdb,if=virtio,index=1,cache=none -net nic,macaddr=54:52:00:4a:ee:0e,vlan=0,model=virtio -net tap,script=no,vlan=0,ifname=tap0 -parallel none -usb -usbdevice tablet -soundhw es1370

And this is the important part with respect to this bug:
-net tap,script=no,vlan=0,ifname=tap0


So I've filed this minor bug just in case, if qemu-kvm changes so that
script= isn't ignored entirely when fd=x is supplied, that libvirt doesn't
start tripping on this.

Not a show-stopper by any means.

qemu-kvm-0.10.4-4.fc11.x86_64
libvirt-0.6.2-11.fc11.x86_64
virt-manager-0.7.0-5.fc11.x86_64