Someone wrote: "The problem with TRT is it validates the whole TRT table before it starts to do the TRT."
As far as I know, TR, but not TRT, can do a trial execution. First, it is only needed if the translate table starts within 256 bytes before a page boundary. But it is needed for TR, as TR modifies the first argument before it knows the extent (on both sides of the boundary) of the second argument. TRT does not modify its argument, and so doesn't have that problem. It might be also for ED and EDMK, though I have never used either. The other SS instructions know the extent of both operands before any data is modified, and can generate the page fault interrupt at that time. -- glen
