by support »
Hello,
A PCIe device is just an entity on the bus that can accept bus requests (reads/writes) into its allocated BAR address space, and also generate such (that is, DMA).
How the device's registers are organized, and their meaning, is a matter of implementation of the device. While there are standardized register mappings for certain device classes (USB, Ethernet, display controllers etc), I'm not aware of any such standard setting for peer-to-peer transmissions. Not saying there is none out there.
Regards,
Eli