On 3/17/2023 10:27 AM, Peter Relson wrote:
And it's fair to wonder. We do "cheat" and turn off facility bits in "our copy" that
relate to facilities that the customer, via MACHMIG, has asked not to be exploited for migration reasons. In
practice, for those facilities it is not relevant whether the facility bit is on, because there is an
operating-system-provided bit that is supposed to be checked to tell if it is OK with the OS for you to use
it. IHAFACL, for example, has this comment for facility bit 129: "Even if this bit is on, do not use the
VEF unless bit CVTVEF is on".
It's good you publish have admonishments like that.
Programmers do not like to load extra base registers if they do not need to.
PSA is conveniently addressable to everyone all the time in any
environment. Getting to the CVT takes overt action *and* an available
register...
--
Phoenix Software International
Edward E. Jaffe
831 Parkview Drive North
El Segundo, CA 90245
https://www.phoenixsoftware.com/
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