Re: MVS under VM\ESA

--- In [email protected], Ivan Warren <ivan@...> wrote:
>
> kerravon86 wrote:
> > 
> > I looked up SIE in the index of the ESA POPS,
> > but didn't see anything.
> > 
> > http://publib.boulder.ibm.com/cgi-bin/bookmgr/BOOKS/DZ9AR006/INDEX?DT=19990630131355
> 
> The Start Interpretive Execution (SIE) instruction isn't described in 
> the Principle Of Operations. However, it is essential to the operations 
> of VM/XA SF and SP, VM/ESA and z/VM. All XA and above systems implement 
> it. Without this instruction, none of those virtualisation hypervisors work.
> 
> > 
> > I guess it's to do with single instruction
> > execution. What's that got to do with 2K
> > vs 4K pages that Dave mentioned?
> > 
> > And surely pretending to protect 4K pages
> > when you're only protecting 2K is going to
> > have an adverse effect on something?
> 
> Your message also indicated how VM/ESA could handle S/370 DAT or S/370 
> I/O.. That's what I was answering to.
> 
> Now...
> 
> When a S/370 program running on a S/370 with 4K protection keys issues a 
> SSK or ISK instruction, it will be greeted with a program interrupt 
> *UNLESS* CR0 Bit 7 is set to 1 in which case, SSK and ISK operate in the 
> same manner as as SSKE/ISKE.
> 
> Since all programs executing as a S/370 SIE guest (i.e. under PR/SM, 
> VM/XA SF, VM/XA SP, VM/ESA (ESA edition, not the 370 edition) or z/VM 
> (up to 4.3)) execute under the protection keys provided by the SIE host 
> which is *ALWAYS* a 4K protection key host (because there is no 2K keys 
> in XA+), then all S/370 guests executing under those environments ALWAYS 
> have a 4K protection key and therefore, SSK/ISK won't work unless CR0 
> bit 7 is set to 1.
> 

Ivan,

I tested plain VM/370 (SixPack 1.2)under VM/ESA 2.4 * and it worked very well.
I even tested Rocky's excellent FullScreen Editor with success.

So non sure if 4K protection key issue applies to VM/370...

Regards.

Paul

* Under Disaster Recory License...