Well, your attitude is perhaps not as cool as one could want. First, I never said I was an expert, and I did point people to the real experts around here. By that I mean in specific, Dave Bond, Dave Rivers, and John Erhman. I have no problem with admitting I am wrong when I am wrong. On the other hand, I am enough of a Texan to know when someone is trying to pick a fight for some unknown and unknowable reason - which is what you seem to be doing. I suggest not doing that, since I simple won't fight with you - why ruin a great place like this for everyone?
Second, it is fairly trivial under Unix or even Linux to limit the execution of an instruction - any instruction you want - and there are several ways to do it. Especially if you remember that the text section (Code Section) is non-modifiable to user level programs. How do I know this? Because I have done it several times. <shrug> Why do you seem to think it is such a difficult thing to do? Didn't you have to write compilers in school? Have you never done system (kernel) level coding under Unix? * -Paul Okay- I admit that it can cause execution time to increase. There are ways to avoid that, such as modifying the loader pre-scan executables while it loads then and before it dispatches them. This is, of course, how most anti-virus programs do run-time protection. Given all that, EPSW works fine on my z/VM system on all the z/Linux variants I use. However, that does not explain why someone else had a problem, and their problem is most like, quite real. I certainly do not have all the facts. -Paul On Jul 8, 2010, at 4:25 PM, Tom Marchant wrote: > On Thu, 8 Jul 2010 19:56:38 +0000, Paul Raulerson wrote: > >> Nope- the machine itself will enforce execution control >> of the instructions. There are various combinations of bit >> settings in the PSW and or control registers that control >> whether the "semi-privileged" instructions can execute or not. > > This thread diverged to semi-privileged instructions only because > you erroneously assumed that the EPSW was a semi-privileged > instruction. It is not. > > In your first append to this thread, you wrote, "I think that may > be a priveledged instruction...." Are you unable to admit that > you made an incorrect assumption? Or perhaps you'd care to tell > us what settings can limit the execution of the EPSW instruction? > > -- > Tom Marchant >
