On Thu, 2 Feb 2023 14:45:31 -0800, Ed Jaffe <edja...@phoenixsoftware.com> wrote:
>On 2/2/2023 2:36 PM, Paul Edwards wrote: >> But on top of that, I was looking for a z/OS change to >> guarantee the high halves were zero. And the new >> information is that I don't need that guarantee. I can >> make my S/370 applications "more-properly-written" >> by taking clear of clearing the high halves themselves, >> without being dependent on z/OS. > >We take exactly the opposite approach because we have been "burned." > >We set Traps(IeaInitArSrb,IeaInitRegsTask) in DIAGxx to ensure the >operating system puts garbage in the ARs and the high halves. > >That way we won't accidentally develop code that depends on these >registers being pre-initialized to zero. Ok, that sounds like a good idea, and again, LA (a S/370 instruction) should cope with clearing that garbage, so that a "properly-written" (or maybe "appropriately-written") S/370 program can protect itself while running in AM64. BFN. Paul. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
