On Mon, 7 May 2018 15:54:01 +0000, Wayne Driscoll 
<[email protected]> wrote:

>>>Changing the documented conventions for using the high-order bit of a
>>>32-bit address word

>>This convention *already* has to change for anyone considering moving to AM64 
>>and using 64-bit pointers.

>Yes, the high bit convention has to change for
>interfaces that accept 64 bit addresses.

Actually, the convention doesn't need to change.
You just need to ensure that the memory where
the parameter list is stored needs to be in
LOC=31 memory rather than LOC=32 or
LOC=64.

In addition, the called routine needs to strip
the high bit with an N to x'7FFFFFFF' instead
of either ignoring it or using an LA to remove it.

Ideally we should start coding in that manner
even if IBM never supports LOC=32 memory
and eventually all our software will be AM64
clean.

BFN. Paul.

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