On Friday, 10/07/2005 at 10:39 AST, "Kielek, Samuel"
<[EMAIL PROTECTED]> wrote:

> >>z/VM 5.2 changes the way CP views memory and the need for CP to keep
> >>dragging pages below 2GB is eliminated.
>
> So does that mean with 5.2 CP was re-written to be completely 64bit? If
> so, that is awesome! If not, is there anything else we need to know and
> what are the gotchas if any?

No, CP was not re-written to be completely 64-bit.  Presentations will be
given at conferences to discuss more of the details, but the general
picture is that:
- More of CP runs in 64-bit addressing mode
- More of CP uses AR mode to access high memory
- The V=R (identity) mapping used by CP to access memory is gone

So, while much of CP remains in 31-bit addressing mode, the way pages are
"translated" by CP modules no longer requres that the page physically
reside < 2GB, but simply be part of CP's 2GB "system execution space".  In
other words, "a miracle occurs in Step 2".

Alan Altmark
z/VM Development
IBM Endicott

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