It was, but Binyamin has a good point. I didn't consider that FLIH would be invoked in real mode, so the hypothetical data-space code could theoretically survive until or unless the system turns DAT on for something other than directly resuming your code.
On Wed, Mar 29, 2017 at 10:51 AM, Tom Marchant < [email protected]> wrote: > On Wed, 29 Mar 2017 17:24:04 +0300, Binyamin Dissen < > [email protected]> wrote: > > >On Tue, 28 Mar 2017 13:04:10 -0400 Steve Smith <[email protected]> wrote: > > > >:>My understanding is that a "data space" is a z/OS construction, the > >:>hardware has no such concept. There's no reason a "dataspace" couldn't > >:>execute instructions as far as the hardware is concerned. Just connect > the > >:>DAT tables as the primary and fire away. Of course, you'd be > programming > >:>on the bare metal, with absolutely no OS support; implying the next > >:>interrupt would blow you away. > > > >No more on the "bare" metal than any other code. > > I think that Steve's point was that there would be no system services > available. > > >Interrupts do not use the > >page0 based off of the STO (whichever) but use the absolute address in the > >prefix register. > > The storing and fetching of old and new PSW use addresses in real page > zero, not virtual page 0, so you are correct, the "STO" (which may not be > a Segment-table origin) is not relevant. > > ALL references to real page 0 and 1 are transformed by prefixing to obtain > the absolute address. Similarly, all references to the real page > identified by > the prefix register and the following page are transformed to absolute > pages 0 and 1. > > -- > Tom Marchant > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN > -- sas ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
