I am using CentOS 5.5 with KVM as a host and have a need for one guest to be able to have promiscuous read access to one port on the physical host (which is an HP BL460 G6 blade server with Intel 2 port 1Gb ethernet mezzanine card.) I initially tried to use PCI passthrough, but I was unable to get it to work. I set everything up as documented in RHEL documentation (http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5/html/Virtualization/chap-Virtualization-PCI_passthrough.html, but I got the following error message: # virsh start c7e1b6_g1 error: Failed to start domain c7e1b6_g1 error: this function is not supported by the hypervisor: Device 0000:0b:00.0 is behind a switch lacking ACS and cannot be assigned Does anyone have PCI passthrough working on a BL460 G6 with CentOS 5.5? I then tried to connect the guest to a bridge. This worked once I did a "brctl setageingtime 0" on the bridge. However, I don't know the best way to make this change persistent. Any suggestions? Is there a better way to do this? Thanks for any input, David