Direct communication between two PCI devices

Question

I have a NIC card and a HDD both connected on PCIe slots in a Linux machine. Ideally, I\'d like to funnel incoming packets to the HDD without involving the CPU, or involving

Answer 1

Assuming that both the NIC card and the HDD are End Points (or Legacy Endpoints) you cannot funnel traffic without involving the Root Complex (CPU).

PCIe, unlike PCI or PCI-X, is not a bus but a link, thus any transaction from an Endpoint device (say the NIC) would have to travel through the Root Complex (CPU) in order to get to another branch (HDD).