Tony Harminc wrote:
[...]
> I objected to porting EPSW way back when, but it seems to be
> a done deal that breaks the S/370 architecture, albeit not in
> any extreme way.
[...]
Your comment regarding it "breaking" the S/370 architecture however, is most definitely not true. It does NOT -- repeat, *NOT* -- break (violate) the [published] architecture.
OK, fair enough. What it does do is make the architecture no longer virtualizable (without some feature like SIE). This 100% virtualizable feature (even for privileged states, and for that matter I/O) was to my knowledge unique among the architectures of the day, and may be still true. Look at the early kluges with i86 and VMWare and such, that had to resort to paravirtualization, where the guest has to cooperate (or the host zaps the guest code on the fly so that it does). I'm not sure that even today i64 is 100% virtualizable, is it?
