At 14:22 -0400 on 09/14/2010, George Henke wrote about Re: z/OS V1.12
differences and z196 (the new mainframe) imp:
Which compromises the entire purpose of the SAVE/RESTORE Register Convention
which has been held "sacred" since the beginning of S/360, PCP, and/or "S"
cubed.
If the 64-bit program calling the 24/31 bit program wants to insure
the integrity of the high end of the registers, it is ITS
responsibility to save them around the call. That is the function of
the 64-bit storing Save Area formats. So long as the called program
wants a old-style Format 1 Save area, the high end is subject to
being altered.
On Tue, Sep 14, 2010 at 1:28 PM, Binyamin Dissen <bdis...@dissensoftware.com
wrote:
On Tue, 14 Sep 2010 11:08:59 -0500 Walt Farrell <wfarr...@us.ibm.com>
wrote:
:>On Tue, 14 Sep 2010 10:26:30 -0500, McKown, John
:><john.mck...@healthmarkets.com> wrote:
:>>> -----Original Message-----
:>>> From: IBM Mainframe Discussion List
:>>> [mailto:ibm-m...@bama.ua.edu] On Behalf Of Paul Gilmartin
:>>> Sent: Tuesday, September 14, 2010 10:23 AM
:>>> To: IBM-MAIN@bama.ua.edu
:>>> Subject: Re: z/OS V1.12 differences and z196 (the new
:>>> mainframe) impacts
:>>> On Tue, 14 Sep 2010 11:04:47 -0400, David Cole wrote:
:>>> >>Except for regs 0,1,15 your assertion is true.
:>>> >>The high halves of those regs are not preserved across any interface
:>>> >>unless otherwise documented.
:>>> >This is in contradiction to a verbal statement he made at a
:>>> >presentation several years earlier wherein he flatly stated that no
:>>> >preexisting AMODE(24/31) program would ever behave differently (due
:>>> >to the widening of the registers) when run in z/OS vis-a-vis OS/390.
:>>> >Unfortunately, I don't have "the video".
:>>> Ah, semantics! Can a program run in AMODE(24/31) in OS/390
:>>> (in a supported configuration) and use grande registers?
:>>Sure. Why not. I use them for 64 bit numbers where I used to use a
register
:>pair. Can OS/390 run on z hardware? I don't remember anymore. But use of
:>Grande registers in application code cannot be stopped by the OS. Of
course,
:>if you call other routines, you'd better store them yourself. Because
:>somebody else might be doing the same.
:>In this context, John, it seems to me that "pre-existing" means "before
:>64-bit registers existed", and thus your programs that use 64-bit
registers
:>don't count. Pre-existing programs would only use 32-bit registers, and
:>would not have any knowledge of the high-halves of the 64-bit registers,
and
:>are not affected by this change.
I have to agree with IBM in this context. Pre-Z programs did not use the
top
half and thus can run unchanged. New Z programs have to take into
consideration that the entire 64 bits of R15-R1 can change.
--
Binyamin Dissen <bdis...@dissensoftware.com>
http://www.dissensoftware.com
Director, Dissen Software, Bar & Grill - Israel
Should you use the mailblocks package and expect a response from me,
you should preauthorize the dissensoftware.com domain.
I very rarely bother responding to challenge/response systems,
especially those from irresponsible companies.
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George Henke
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