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Re: Can a VM machine ...

 



On Thu, Dec 1, 2022 at 8:27 PM Fish Fish <david.b.trout@...> wrote:
David Durand wrote:


> and I suspect that there are very few (if any) surviving programs
> where DIAG is used for anything other than communicating with CP.

I'm not so sure. I suspect they're probably are. Hercules for instance supports two different "Power Off" diagnose instructions: one for the 9221 and the other for 4361 and 937X (e.g. 9371).
Cool! I've just never seen doc about that.
?
> Given that, I think an argument could be made that Hercules can
> just as well print a message on the console when DIAG is executed
> in supervisor state, rather than signalling an exception. This
> would amount to treating Hercules as a new model,

Hercules is ALREADY a "new model". Hercules is a Hercules model mainframe. It's its own unique model of mainframe, unlike any other.
yep.?
> and defining DIAG for that model in a "harmless", potentially
> helpful way. The Hercules console function has to be optional
> for security reasons, but? if the conditions are met for the
> CP DIAGNOSE '008' case, the option could choose between printing
> a message (DISABLED HERCULES CONSOLE REQUEST IGNORED: 'command',
> and the current extension.

I believe the DIAG8CMD option already covers that. But instead of a "request ignored" message, you get an Operation Exception Program Interrupt. (Or is it a Specification Exception? I forget!)

?Previous thread indicates Operation Exception.

> Depending on what assumptions are made by the implementation of
> HCP, it might make sense to alter registers to reflect failure.
> Since the architecture allows anything, and requires nothing,
> the Hercules behavior of DIAG could be defined in a way that
> would not break HCP, if present.

I guess I'm coming to this party late. What exactly is the problem (issue) again?

The complaint was from Olaf
From:

Rhialto?rhialto@...???

On Mon 28 Nov 2022 at 18:41:21 -0000, Dave Wade wrote:
> Its already there. HCP command.

There is just one thing wrong with it: if it is not allowed in the
hercules config file (with DIAG8CMD ENABLE), VM crashes:

/hcp test? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
/19:54:55? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
HHC00009I RRR...RING...GGG!? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
/? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
/? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
/? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
/19:54:55 DMKDMP908I SYSTEM FAILURE; CODE PRG006 PROCESSOR 00? ? ? ? ? ? ? ? ? ?
/? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
HHC00009I RRR...RING...GGG!? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
/? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
/? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
HHC00009I RRR...RING...GGG!? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
/? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
/? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
/VM/370 System Restart? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
/?

It just occurred to me that the community edition out-of-box experience?would be better if instead of crashing VM, the Hercules console said something like:?
DIAG8CMD DISABLED. Hecules?command ignored, command was: test
It could even point to manual or config more explicitly. Emulation is no worse, but there's no chance that running an exec that uses HCP would crash CP.

I'm not able to find a lot of mainframe?time right now, though I am reading the list, and it seemed like a reasonable idea. I don't know that I will be able?to manage a pull request any time soon, or whether people would like the idea.

? -- David
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