On Tuesday, 07/30/2002 at 01:20 AST, Dennis Musselwhite/Endicott/IBM@IBMUS wrote: > Hi, > > Lionel Dyck asked: > > When you dedicate an osa-e to a linux guest > > does that preclude vm from using the same osa-e? > > When you dedicated an OSA Express to a VM guest, you really just > dedicate a few of the I/O ports to the guest. No other guests can > use those specific I/O ports, but they may use other I/O ports on > the same OSA Express card. > > The (in)famous portname becomes really important at that point. > If the new guest is not configured with the portname that's already > in use on the adapter, the new guest will not be able to initialize > the interface.
Let's be clear on OSA terminology, Dennis. A PORT is the thing you plug the network cable into. (There is no such thing as an "I/O port".) The PORT is accessed through UNIT ADDRESSES on the CHPID which have associated DEVICE NUMBERS from the IOCDS. And a CARD (OSA Feature) may have 1 or 2 CHPIDs on it. The number of chpids per card is simply a function of technology density. Guests, CP, or LPARS share a port by simply doing I/O to the same chpid and specifying the same port number (in case chpid has multiple ports). Well, not quite that simple, since, as you noted, for QDIO you also have to have the "magic cookie" (port name) to indicate that you have a clue about what you are doing. (The port name does not apply to LCS mode.) Alan Altmark Sr. Software Engineer IBM z/VM Development
