On Thu, 27 Jun 2013 09:39:01 -0500, Tom Marchant wrote:
>On Wed, 26 Jun 2013 22:45:50 -0700, Ed Jaffe wrote:
>
>>AFAIK, there is only one 4K range of virtual addresses guaranteed to
>>generate 0C4 now and forever: 7FFFF000 - 7FFFFFFF.
>
>I didn't know that. Is it documented anywhere?
>
>The 4K range from 00000000 - 00000FFF is key 0 storage and, as such,
>is protected from stores by unauthorized programs.
>
This thread appears to have drifted from a discussion of 7FFFF000
to a discussion of PSA. But a search of z/OZ publibz for the former
finds a few tantalizing references such as:
...
152 (98) ADDRESS 4 OUCBWORKQTOKEN
Server Environment
Address Space Queue
Entry pointer or
7FFFF000
... but no definitive statement that that page is forever excluded,
nor whether it's a hardware or software feature, and of course no
mention of other operating systems.
Is there any such restricted address in AMODE 24?
And I suspect Shmuel's statement may apply: You're not
guaranteed an 0C4 if a SPIE is in effect.
-- gil
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