PCI passthrough with virtualbox

Question

Since vbox has troubles with network latency we want to try pci passthrough of a network card. The docs say we need to "VBoxManage modifyvm "VM name" --pciattach 02:00.0@01:05.0", which means attaching the pci device in question to the guest.
But what about de-taching it from the host? The docs do not mention this at all. Has anybody real experience with this? Do we need to detach the device from the host or does vbox do that automatically in the background when attaching it to a guest?

Answer 1

If the host is Windows, goign to Device Manager and "disabling" the device would do the trick, I think. It essentially turns off the windows driver for it.

Answer 2

This should help.
http://lwn.net/Articles/143397/