On Sat, 28 Nov 2015 09:17:01 -0800, Charles Mills <charl...@mcn.org> wrote: >I am dealing with future machines by assuming that anything not in my table >is of an architecture level higher than those I know about. For my >application this is a safe assumption.
The problem you have is that the premise is false. A machine type can be thought of as a point-in-time collection of architectural features, whose existence is surfaced by the STFL and STFLE instructions. At GA2 we often add new features, so a table would have to look at "GA1" and "GA2". While it is rare for things to be removed from the architecture, it does happen (the old Vector facility). And there are even functions in the system that allow a concurrent MCL to signal the addition or deletion of a feature. >VM does not generally alter the problem instruction set of a guest, right, >nor change the machine type number? (I recall that one can change the serial >number.) If VM is running on a z196, every guest sees a machine type of >2817, correct? VM neither adds store on condition to a machine that does not >support it at the hardware level, nor deletes it from a machine that does? In general, this is not true. z/VM masks off the features reported by STFL and STFLE such that the guest sees only those that are supported by both the processor and z/VM (for guest exploitation). Further, in a Single System Image cluster, relocation domains can cause a guest on z13, say, to see only the features and functions of a z12 or z196/114, a fencing mechanism enforced by the Interpretive Execution Facility. The guest will see a machine type of a z12 rather than that of the physical CPU it is running on. z/VM also adds architecture, as demonstrated by the STORE HYPERVISOR INFORMATION (STHYI) instruction, represented by a STFLE bit, the IUCV instruction (hi-order byte of Processor ID = FF) and different set of DIAGNOSE subfunctions (again, from STIDP[0] = FF). Alan Altmark z/VM Consultant ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
