Behaviour of instructions not supported on z390
Abe Kornelis
Dear all, Now that V1.8.0 is out, the development team are beginning work on the next set of changes. For me, that means I'm looking into a set of changes to make "unsupported instructions" behave consistently. For example, most privileged instructions are not supported on z390. Making these instructions behave consistently means we need to define what the desired behaviour should be. Currently, we some of these instructions cause a S0C1 abend, some are implemented as a no-op, and some are partially implemented. Ideally, we would fully implement these instructions in a meaningful way, but that appears out of reach for the moment. Therefore I would suggest the following: - in problem mode, issue a privileged-operation exception or a special-operation exception, depending on the instruction's definition in the PoP. - in supervisor mode (which we do not support yet!) issue a special-operation exception - unless/until we have a better implementation. It's a rather arbitrary choice, so please do feel free to come up with a better suggestion! Kind regards, Abe ===
d...@higgins.net
Abe, all
I think we should abort all supervisor instructions and currently unsupported instructions. The preferred method to perform supervisory functions with z390 is via svc calls which in tern get matted into java functions for the 3 different supported host environments: Windows, Linux, and Mac OS.
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Abe Kornelis
Don,
fair enough - does that mean you concur with my proposal below?
That would be pretty close to the set of changes that John and I
are currently working on.
Kind regards,
Abe
===
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d...@higgins.net
Abe, John, all
How about 2 abend codes:
- S0C2 for privileged opcode not supported
- S0C1 non-privaledged opcode not supported yet
Today I’ve started on issue 300 to add MGRK support. It currently causes S0C1.
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