Off list reply. Maybe this answers your question.
From Principles of Operation, Appendix A, examples using CS, CDS. An
"Add to Free List" routine is given. Code is as follows:
ADDQ LM 0,1,0(4)
TRYAGN ST 0,0(2)
LR 3,1
BCTR 3,0
CDS 0,2,0(4)
BC 7,TRYAGN
Paragraph following code sample states
"Note that the LM at location ADDQ would have to be CDS if it were not
for the rule concerning storage-operand consistency. This rule requires
the LM to fetch an eight-byte operand aligned on a doubleword boundary
such that, if another CPU changes the doubleword being fetched by an
operation which is also at least doubleword-consistent, either the
entire new or the entire old value of the doubleword is obtained, and
not a combination of the two."
Regards,
John Ganci
Binyamin Dissen wrote:
I would like to guarantee a concurrent load of two words on a double word
boundary.
Will LM serialize the doubleword?
Or must I something hokey like a CDS which appears to do a concurrent load if
the result is not equal.
Doing a L followed a PLO/CompareLoad seems the absolute worst choice.
--
Binyamin Dissen <[EMAIL PROTECTED]>
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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