-----Original Message----- From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On Behalf Of Thomas Berg Sent: Friday, August 18, 2006 8:43 AM To: [email protected] Subject: Re: The Fate of VM - was: Re: Baby MVS??? <SNIP> (I had the impression that there were very little support(ing developement) needed for VM, especially compared to MVS.)
Thomas Berg <SNIP> IEF (Interpretive Execution Facility) was done for VM to provide the SIE instruction (Start Interpretive Execution). A super EXecute and BASR/BALR/BASSM type thing. It is what allows VM to NOT have to shadow "MVS" any more. There's some pretty hefty and serious micro-code to implement that. And because it has gone through at least 3 upgrades (XA to ESA to z/ARCH), that's quite a bit of support for VM that is not even in CP itself. And this is on-going development as things about the channel architecture changes, certain instructions come along (e.g., SCLP - Various of the B2xx allow you to talk to the service processor -- these have to be intercepted...) that affect the CEC, etc. Then there are various instructions that are done just for VM to dispatch guests that MVS, VSE and TPF don't make use of (at Amdahl we had various assist instructions that I believe IBM was also doing just for VM). This is another development area that must be done in micro-code (does IBM also use vertical micro-code as well as horizontal?). So there's more to VM development than one might think. Lastly, there's PR/SM, which at first WAS VM under the covers (I can't tell you how many people told us [when I was at Amdahl] about how they could get into "CP" when running PR/SM). I do not know if PR/SM is still a flavor of VM. But it makes use of some of those "Hypervisor" instructions that VM seems to have to know about so that z/OS BCP developers can do their thing... Later, Steve Thompson ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
