#     Several tips for HOST configuration:
#
#     Alternative I: HOST system has no driver for VIDEO CARD for passthrough.
#
#     1. cat /etc/modprobe.d/vfio.conf 
#        options vfio-pci ids=1002:67b0,1002:aac8
#
#     2. cat /etc/udev/rules.d/80-my-qemu.rules 
#        SUBSYSTEM=="vfio", OWNER="root", GROUP="kvm"
#
#
#     Alternative II: HOST system has driver for VIDEO CARD.
#
#     1. cat /etc/modprobe.d/qemu.conf
#        # reserve hardware with vfio_pci for GUEST
#        install nvidia        /sbin/modprobe vfio_pci; /sbin/modprobe --ignore-install nvidia
#        install snd_hda_intel /sbin/modprobe vfio_pci; /sbin/modprobe --ignore-install snd_hda_intel
#        install vfio_pci      /etc/modprobe.d/sh/qemu.sh
#
#     2. cat /etc/modprobe.d/sh/qemu.sh
#        #!/bin/sh
#
#        # reserve VIDEO CARD and SOUND CARD (HDMI) for GUEST
#        echo 'vfio-pci' > '/sys/bus/pci/devices/0000:05:00.0/driver_override'
#        echo 'vfio-pci' > '/sys/bus/pci/devices/0000:05:00.1/driver_override'
#
#        # reserve usb for guest
#        echo '0000:02:00.0' > '/sys/bus/pci/devices/0000:02:00.0/driver/unbind'
#        echo 'vfio-pci'     > '/sys/bus/pci/devices/0000:02:00.0/driver_override'
#
#        # modprobe vfio-pci should be before all other modprobe
#        /sbin/modprobe --ignore-install vfio_pci
#
#     3. cat /etc/udev/rules.d/99-qemu.rules
#        GROUP="kvm", MODE="0660", ACTION=="add", DEVPATH=="/devices/virtual/misc/vhost-net"
#        GROUP="kvm", MODE="0660", ACTION=="add", DEVPATH=="/devices/virtual/vfio/20"
#
#     4. cat /etc/rc.conf | grep rc_ulimit
#        rc_ulimit="-l unlimited"