My understanding is that it is automatic when you are VM guest, and you
can't LRG unless you are a guest, so z/OS (if it supported LGR) does not
have to do anything.
Tony Thigpen
Peter Relson wrote on 3/27/19 9:32 AM:
<snip>
When a z/VM guest issues the STFLE command, z/VM intercepts it and
returns the lowest-common-denominator value for all processors available
for LGR.
</snip>
I think this implies that any user of LGR must have "pre-set" the
definition of "processors available for LGR" before IPLing an image (such
as z/OS). If that's the expectation and the reality, then I agree. I was
thinking of some change "after IPL", but perhaps that is what cannot
happen.
For example, if you have a z14 but have defined a rule such as "I might
want to use LGR down to a z13" and that rule gets applied to an IPLing
z/OS, then only the z13 facilities would show up. Can there be such a
(hypothetical) definition set up for each individual guest, as opposed to
there being one definition for all guests (the latter seeming far too
restrictive)?
Peter Relson
z/OS Core Technology Design
