On 18 October 2016 at 18:27, Peter Hunkeler <p...@gmx.ch> wrote: > Below discussion triggered a question I could not answer by RTFM. I had never > thought about this before in this detail, > but now that I do, I wonder if the following is correct. > > Program allocates >4k of virtual storage. The real frames backing it may or > may not be contiguous. The program wants to > use this area with some interface (I/O, etc) that will use real addresses > when accessing the storage, so it does a PGFIX. > PGFIX would move the possibly non-contiguous frames guaranteeing the area is > backed by contiguous frames. After all, > the interface using real addresses would expect the the frames to be > contiguous. > > Am I wrong? I would have expected to find this documented with the PGFIX or > PGSER FIX macros, but did not find it.
I do not believe there is such a service documented. As Jim Mulder pointed out, there are 1M pages available above the bar, but that's relatively new stuff. And there are unexposed RSM services to manage pairs of frames (and quads, I think he said). If you want to do I/O to your real storage, that is what IDAWs are for. Perhaps there are undocumented (or at least not publicly documented) IBM facilities -- I'm guessing things like crypto, compression, newer non traditional I/O -- that take real addresses and need more than a page at a time, but I don't know of any. In this sense, VM's Diagnose interface is an outlier. Tony H. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
