Ray, I think the OP and Chris were referring to a situation where the target address space is being "snooped" - rather than sharing its memory by a controlled and approved x-memory linkage. There are example code snippets out there in the public domain that attempt to access private storage in a foreign non-swap ASID in AR-mode after adding an ALET using CHKEAX=NO on the ALESERV. This technique is not to be encouraged and will eventually end in tears for someone.
Rob Scott Lead Developer Rocket Software 275 Grove Street * Newton, MA 02466-2272 * USA Tel: +1.617.614.2305 Email: rsc...@rs.com Web: www.rocketsoftware.com -----Original Message----- From: IBM Mainframe Discussion List [mailto:ibm-m...@bama.ua.edu] On Behalf Of Ray Overby Sent: 11 May 2010 15:52 To: IBM-MAIN@bama.ua.edu Subject: Re: Accessing Cross Memory Storage in REXX My understanding is if the target address space is non-swappable then you can safely use non-srb code to obtain access to the other address space's private area. I believe the unpredictability comes when the target address spaces are swappable. Depending upon your application requirements non-srb code may in fact work. For example, address spaces with a system LX that support space switch pc routines will always be non-swappable. If your application required data from these address spaces you should be ok. There are other address spaces that normally run non-swappable. However, you could not access all address spaces with this technique. For swappable address spaces you should use SRB code. As usual, it depends upon your application......... Chris Craddock wrote: > On Mon, May 10, 2010 at 4:37 PM, Rick Fochtman <rfocht...@ync.net> wrote: > > >> -----------------------------<snip>------------------------------------ >> >> Highly unlikely unless I'm missing something obvious. The only LEGAL way to >> access memory in some other address space is via an SRB. You need to be in >> sup state and key zero to schedule an SRB and REXX runs key 8 and problem >> state. But if we're allowed to cheat then I'll play :-) >> >> PS> I didn't know there were any mainframe people at Queens... >> -------------------------------<unsnip>------------------------------- >> Not strictly true, but the mechanisms are NOT for the meek! I've found >> other ways but in the interests of safety, I'll not share them. >> >> > > > Notice that I said "Legal". Nothing else is supported by the z/OS software > architecture - regardless of whether something else is possible under the > hardware architecture. Any grinning idiot with an APF library can study PoPs > and contrive ways of gaining addressability to some other address space, but > since z/OS doesn't know (or allow!) what you would be doing, the results are > most kindly described as "unpredictable". > > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
