Egress(outbound) Ingress(inbound)
as Root as endpoint as Root as endpoint
Posted mem wr req posted mem wr req posted mem wr req posted mem wr req
non-posted mem rd req non-posted mem rd req non-posted mem rd req non-posted mem rd req
mem rd completion mem rd completion mem rd completion mem rd completion
cfg req (type 0/1) cfg completion(type 0) cfg completion(type 0/1) cfg req(type 0)
io req io completion io completion io req
pwr mgr req to endpoint pwr mgr msg to root pwr mgr msg from endpoint pwr mgm req from root
msi msg/intx msg
err msg/PME_TO_ACK