On Sat, 16 Aug 2025 23:55:47 +0300, Binyamin Dissen 
<[email protected]> wrote:

>:>ROTFLOL, this is why RMODE capability shouldn't be documented as a 
>requirement. Out of sight, out of mind.
>What does RMODE have to do with it? My statement was regarding AMODE.
>The R14 values for both 24 & 31 bit are appropriate for BSM and coincidentally 
>BR.

IBM has geniuses developing simple yet effective solutions to problems. RMODE 
plays a huge role in AMODE but is not always blatantly obvious. 

For ATTACHX, what do we know about R14 (return address) because RMODE64 is 
prohibited? Since the load module is required to be RMODE31 or RMODE24, R14 
will always be a valid address below the bar (31-bit). It may be in a 64-bit 
register but is guaranteed to be a valid address below the bar. IBM does not 
document 64-bit R14 because it is not possible. You can argue it should be 
documented but RMODE restriction tells us the valid R14 values.

Ask yourself why is LOC=RES the default for STORAGE OBTAIN. Again, the RMODE 
(PSW address) should be valid for the AMODE. There are assumptions we can make 
because of the RMODE.

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