Private Devices and OS support

["Vogt" <vogt@inet.dpt.com>]

     We are designing an add-in card with multiple PCI devices behind a PCI 
     to PCI bridge and have a couple of concerns. The devices behind our 
     bridge will be controlled by another device on our secondary bus, not 
     by the host. The controlled devices will have the ability to transfer 
     data to/from the primary bus.
     
     1. Since the BIOS and OS will be able to see our devices, are there 
     any rules about moving the addresses of these devices? One concern is 
     that the OS, such as WIN-NT/95 might decide to move our secondary 
     devices addresses while our card is doing background tasks. (The 
     scenario might be hot-docking) In other words, there is no outstanding 
     command that the OS is aware of, yet our card is still moving data 
     internally. Should the OS reprogram one of our secondary BARs at that 
     time, the result would be disastrous. Are there any rules for this 
     scenario? What is Microsoft's policy on this?
     
     2. What is the PCI-SIG policy of hiding the devices from the BIOS/OS? 
     Some of the newer bridges have features which enable this type of 
     behavior, however, this creates an address space "hole" in the PCI 
     address map for the hidden devices. 
òt	d