On Mon, 17 Oct 2016 10:08:50 -0700, Ed Jaffe wrote:
>>
>> Hmmm... What happens if AMODE 31 code issues LRA and the real address
>> is above the bar? Program check? Or does LRA simply (always?) load a
>> 64-bit register? Is there an LRAG instruction?
>
>Why not take at least a cursory glance at Principles of Operation before
>asking such questions publicly?
>
You're right; thanks. GIMF. (Oops; the Urban Dictionary says that doesn't
mean what I expected.) I find:
z/OS 2.2.0
z/OS MVS
z/OS MVS Programming: Assembler Services Guide
Understanding 31-bit addressing
Understanding the use of central storage
Central storage considerations for user programs
Load real address (LRA) instruction
Woe be unto anyone who did LRA; LA in AMODE 24 (But why?. And it
doesn't discuss AR mode. Perhaps elsewhere, but my curiosity is exhausted.
Which leaves a historical question. Was AMODE 31 antedated by the
availability of real storage >16 MiB, or was AMODE 64 antedated by
the availability of real storage >2GiB? How did LRA(G) operate in
those eras?
And in a virtual guest with shadow page tables, does LRA return the
real real address or a virtual real address? I suppose it's all emulated
by CP anyway, so it depends. Or maybe SIE. My head hurts.
Thanks,
gil
----------------------------------------------------------------------
For IBM-MAIN subscribe / signoff / archive access instructions,
send email to [email protected] with the message: INFO IBM-MAIN
