VMDirectPath I/O allows a guest operating system on a virtual machine to directly access physical PCI and PCIe devices connected to a host. Each virtual machine can be connected to up to two PCI devices. PCI devices connected to a host can be marked as available for passthrough from the Hardware Advanced Settings in the Configuration tab for the host.
VMDirectPath allows guest operating systems to directly access an I/O device, bypassing the virtualization layer. This direct path, or passthrough can improve performance for VMware ESXTM systems that utilize high‐speed I/O devices, such as 10 Gigabit Ethernet.
VMware unveils VMDirectPath technology, Intel to support it with Nehalem: