The product is a full TCP/IP stack and suite, we are doing a LOT of
cross-memory moves using access registers in our vendor product. (No
SRBs in VSE. No 'real' PS-ss, either, but we do fake some of those.)
The product is BSI IPv6/VSE.
We don't know why, and it should never happen, but occasionally, the
ALET (for the partition we are talking with) will change between calls.
(If I had not seen it in the traces with my own eyes, I would not
believe it happened either.)
We were not aware of the TAR instruction, so our work-around has been to
just re-acquire the ALET each call, which is CPU expensive. We think the
TAR instructions might be a CPU cheap answer.
Tony Thigpen
Binyamin Dissen wrote on 1/14/25 11:41 AM:
A standard application job will have an AX of zero.
On Tue, 14 Jan 2025 11:02:01 -0500 Tony Thigpen <[email protected]> wrote:
:>All,
:>
:>This instruction might just help me with a software product issue on VSEn.
:>
:>Can someone post an example the correct setup for R2 (the EAX) in a TAP
:>test, as used on z/OS?
:>
:>
:>Tony Thigpen
:>
:>John Dravnieks wrote on 1/14/25 2:38 AM:
:>> Hello
:>>
:>> I have come across some usage of the Test Access instruction (TAR) in a
problem state program - given that TAR is documented in Chapter 10 of Pop (usually
the supervisor state instructions generally only of use to the operating system) I am
concerned that TAR is being used incorrectly
:>>
:>> The code correctly loads an access register into AR7 and then has this:
:>> TAR R7,R0 Valid access register?
:>> JP AOK Yes
:>>
:>> The second operand R0 refers to general register 0, which has a positive
value of 32768 or less - so bits 32-47 of gpr0 will be zero so the effective EAX used
by TAR will be zero.
:>>
:>> My question is is this a valid way to test the validity of an access
register? And should it also be checking for a condition code of 1 as well ?
:>>
:>> Kind regards
:>> John Dravnieks, 21CS Software
:>> (posted here at suggestion of Binyamin Dissen)
--
Binyamin Dissen <[email protected]>
http://www.dissensoftware.com
Director, Dissen Software, Bar & Grill - Israel
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