Yes, z/VM has a bar. With our first 64-bit version, there were some restrictions that virtual machine pages for guest I/O had to be under the bar. That was rather unpleasant for Linux that does not use dedicated memory areas as I/O buffer. It got crowded under the bar. And the 32-bit Linux s390 had some challenges because a process would only be able to span 2GB where the x86 folks could have 4GB. Even though we kept kernel memory out of that 4GB, we did run a bit sort with Java for example.
Don't think Linux folks refer to either as the "bar" but they're probably not of legal age yet ;-) On 5 November 2014 21:10, John McKown <[email protected]> wrote: > On Wed, Nov 5, 2014 at 1:03 PM, Paul Gilmartin < > [email protected]> wrote: > > > On 2014-11-05, at 05:10, Tony Thigpen wrote: > > > > > And z/VSE followed the same pattern as z/OS. > > > > > > And, as a little extra, this is why the 31/64 line is called a BAR, not > > a LINE. The unusable addresses are what is in the BAR. So, you can be > above > > the bar, or below the bar, but not in the bar. (No drinking allowed. > :-) ) > > > > > This been discussed, tediously, in these lists. The statement, including > > from some IBM employees, perhaps unofficial, is that the BAR is an > > infinitesimal boundary immediately below 2GiB. Any address >= 2GiB > > is considered *above*, never in, the BAR. > > > > Nevertheless, as long as z/OS and z/VSE exclude 2GiB <= address < 4GiB, > > I prefer your interpretation. Is "bar" prevalent in VM or Linux argot? > > > > On the Linux-390 forum, I've never seen the use of "bar" in this context. > Only 64 bit mode or 31 bit mode. In the same context as the x86_64 or i386 > mode for Intel. > > > > > > > -- gil > > > > > > -- > The temperature of the aqueous content of an unremittingly ogled > culinary vessel will not achieve 100 degrees on the Celsius scale. > > Maranatha! <>< > John McKown >
