There is no restriction on AR mode with AMODE 64.  See DAT Address Translation 
in Chapter 3 of the POPS manual, specifically the right side of page 3-36

As determined by its address-space-control element,
a virtual address space may be a 2G-byte space
consisting of one region, or it may be up to a 16Ebyte
space consisting of up to 8G regions. The RX
part of a virtual address applying to a 2G-byte
address space must be all zeros; otherwise, an
exception is recognized.

I also see no reason why AMODE 64 should be slower than AMODE 31, other than 
because you are probably hitting a lot of storage and having page faults.

Chris Blaicher
Technical Architect
Mainframe Development
Syncsort Incorporated
2 Blue Hill Plaza #1563, Pearl River, NY 10965

P: 201-930-8234  |  M: 512-627-3803
E: [email protected]

www.syncsort.com

CONNECTING BIG IRON TO BIG DATA

-----Original Message-----
From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf 
Of Paul Gilmartin
Sent: Tuesday, March 28, 2017 1:30 PM
To: [email protected]
Subject: Re: 64 bit execution above the bar

On Tue, 28 Mar 2017 13:04:10 -0400, Steve Smith wrote:
>
>I presume IBM would like to deprecate and retire dataspaces completely,
>although the eternal backward-compatibility may prevent that for 100
>years or more.
>
(Wow!  We're halfway there!)

My impression, also.  Is there anytning possible with AR-mode that can't be 
done with AMODE 64?  (May I assume that AR mode-mode and AMODE 64 are mutually 
exclusive?)

What's the peformance consequence of AR-mode?  I might expect it to be slower 
than AMODE 31 but faster than AMODE 64.

I feel similarly about page protection keys.  Segment protection should make 
them obsolete.

-- gil

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