Hi Alan,

> This isn't how DIAGNOSE instructions work.  Instead of worrying about
> converting user privclass to IBMCLASS and associating with the running
> DIAGNOSE, it's done in the more primitive hindbrain of CP.
> Architecturally, a DIAGNOSE is associated a SINGLE privilege class (or
> privclass ANY).  They aren't supposed to change behavior based on
> privilege class (directory OPTION, maybe, but not privclass).
>
> DIAGNOSE 2FC is violating that architecture.  I would suggest a PMR so
> that you can discuss with Development whether that violation is Right and

> Proper.

I guess the challenge with DIAG 2FC is that not every issuer is necessarily
supposed to see guest information beyond themselves. So while I agree with
your assessment I see reasoning in the approach taken ...

Best regards
Ingo

Linux on 390 Port <[email protected]> wrote on 20.05.2016 17:19:01:

> From: Alan Altmark <[email protected]>
> To: [email protected]
> Date: 20.05.2016 17:19
> Subject: Re: [LINUX-390] hyptop question
> Sent by: Linux on 390 Port <[email protected]>
>
> On Friday, 05/20/2016 at 06:41 GMT, Karl Kingston
<[email protected]>
> wrote:
> > > For z/VM, the guest virtual machine must have privilege class B
> > > or, preferably, a locally-defined privilege class that contains
> > > diagnose 2fc.
> >
> > How does one do this?    Don't like giving my linux guests access to
> CLASS
> > B so I would like to make my own class and give that to the user.
>
> Well, isn't this embarrassing... (blush) (look down) (kick rock)   You
> can't.  I keep forgetting that DIAGNOSE instructions are architecturally
> different than commands.
>
> (For a fascinating description of how CP commands and DIAGNOSE
> instructions are processed, keep reading!)
>
> The system supports privclass-qualified versions of a command.  When you
> enter a command, the highest level (A->9) for which you have the assigned

> privilege class will run.  That is, if a command has a class B version
and
> a class G version, then if you have class ABG, the command will be
> qualified as class B.  If you had class AG, then the command will be
> qualified as class G.  That's the last time CP looks at the issuer's
> privclass.  The system instead looks at the command qualifier.  We refer
> to the command qualifier as the "IBMCLASS".  That is, the IBM-defined
> privilege class associated with the version of the command that's
running.
>  The MODIFY COMMAND command lets you change the association between the
> user privclass and the IBMCLASS.
>
> This all gets resolved before the command actually runs, eliminating any
> need for CP to worry about user privclass.  He just cares about the
> IBMCLASS of the command that's running.  This allows a single entry point

> to handle the command.
>
> This isn't how DIAGNOSE instructions work.  Instead of worrying about
> converting user privclass to IBMCLASS and associating with the running
> DIAGNOSE, it's done in the more primitive hindbrain of CP.
> Architecturally, a DIAGNOSE is associated a SINGLE privilege class (or
> privclass ANY).  They aren't supposed to change behavior based on
> privilege class (directory OPTION, maybe, but not privclass).
>
> DIAGNOSE 2FC is violating that architecture.  I would suggest a PMR so
> that you can discuss with Development whether that violation is Right and

> Proper.
>
> Alan Altmark
>
> Senior Managing z/VM and Linux Consultant
> Lab Services System z Delivery Practice
> IBM Systems & Technology Group
> ibm.com/systems/services/labservices
> office: 607.429.3323
> mobile; 607.321.7556
> [email protected]
> IBM Endicott
>
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