On Thu, 11 Feb 2016 09:26:00 -0600, Paul Gilmartin <[email protected]> wrote:

>On Thu, 11 Feb 2016 05:39:33 -0600, Tom Marchant wrote:
>>
>>For example, z/Architecture uses 64-bit addresses, so all of those places 
>>where an 
>>address is defined are 64 bits wide. PSW address is an obvious one. Also, the 
>>locations 
>>for the old and new PSW for SVC, I/O, External, Restart, Machine Check, and 
>>Program 
>>interruptions now require 16 bytes. Dynamic Address Translation tables (page 
>>and 
>>segment tables, etc.) require 64 bits for addresses. Likewise for Control 
>>registers.
>> 
>Does this imply no more scrunched PSWs?  Execution above the bar becomes 
>possible?
>64-bit LPA?

Why would it imply that? Those are all z/OS software constructs or limitations, 
not anything to do with the hardware as far as I know. They're already possible 
with today's zArchitecture, if z/OS wanted to allow/implement them. 

Of course, the scrunched PSWs are also for application compatibility, so doig 
away with them would be a big change for everyone, not just z/OS.

-- 
Walt

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