The main takeaway should be: If you are running z/OS 1.4 or earlier in 31 bit mode, test running it in 64 bit mode. Just in case it won't, get a z/13 and you should be able to run it in 31 bit mode about another 8 years with supported hardware.
On Wed, Feb 10, 2016 at 4:09 PM, Tony Harminc <[email protected]> wrote: > On 10 February 2016 at 15:50, Joel C. Ewing <[email protected]> wrote: >>> Why do you think that SIE would not continue to provide virtual >>> ESA/390 support? Today, when z/VM is running in zArch mode on the >>> metal on e.g. a z12, it can surely have an ESA/390 mode guest OS. I >>> see no reason that wouldn't continue just because the host processor >>> doesn't IPL in ESA/390 mode. >>> >>> Tony H. >>> >>> >> Well that was sort of my first thought too, but the actual wording in >> z/VM Statement of Direction was that "the IBM z13 server family will be >> the last to support ESA/390 architecture mode", not that it wouldn't >> support ESA/390 mode on IPL. That sure sounds like there will no longer >> be any hardware ability to switch ARCHLVL mode, and that z14 and later >> will run only in ARCHLVL2 mode. > > Well I don't know what IBM has actually said, or what they mean, so > I'm speculating as much as you are. Hopefully one of our friendly > IBMers will step in and clarify. But my understanding of "the IBM z13 > server family will be the last to support ESA/390 architecture mode" > is simply that on z14+ the IPL sequence will not start in or pass > through ESA/390 mode, and it will not be possible to issue a SIGP to > set ESA/390 mode. OK, but none of this suggests that a guest under SIE > will not be able to run in ESA/390 mode. Perhaps the IPL will take > some assistance from z/VM, but no one cares if that has high emulation > overhead. > > BTW, this whole "switch architecture modes on the fly" reminds me of > the famous Gordon Letwin "turning the ignition off and back on when > the car's doing 60 MPH" scheme for the Intel 286 on OS/2. Only it's > architected, rather than being a fortuitous kludge. > > http://www.google.com/patents/US4825358 > > Tony H. > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN -- Mike A Schwab, Springfield IL USA Where do Forest Rangers go to get away from it all? ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
