On Mon, 14 Dec 2009 15:52:59 -0600 Chris Craddock <[email protected]> wrote:
:>On Sun, Dec 13, 2009 at 8:49 PM, David Stephens < :>[email protected]> wrote: :>> This (very rough draft) article "Cross Memory Communications for Beginners" :>> may help. :>> http://www.longpelaexpertise.com.au/ezine/CrossMemoryBeginners.html :>> David Stephens :>> Lead Systems Programmer :>> [email protected] :>> www.longpelaexpertise.com.au < :>> http://www.longpelaexpertise.com.au/images/logo.gif> :>> Longpela Expertise - System z Mainframe Consultants :>> Read new expert Mainframe articles every quarter in our LongEx Mainframe :>> Quarterly <http://www.longpelaexpertise.com.au/ezine> :>Corrections for the article; :>(1) SRBs do NOT always run disabled. They are initially dispatched enabled :>for interrupts just like any other piece of work. They only become disabled :>(legally) if they obtain a spin lock such as the CPU lock. When they release :>the lock they are reenabled (again, like any other piece of work) :>(2) SRBs do not ALWAYS run before any TCB in the address space where they :>are dispatched. SRBs that are scheduled into an enclave run at whatever :>priority that enclave happens to be assigned at any given moment according :>to the service goal and attainment. That priority could be higher (or LOWER) :>than any other unit of work in the address space (both TCB and SRB) :>(3) Using AX=1 and SSAR to another address space is not very clearly :>documented by IBM because it is a violation of the MVS xmemory architecture. :>You DO NEED that "complicated synchronous cross memory" code to be safe. > :>(4) ASC mode does not remove the need for the "other" address space to be :>swapped in. You can't reliably access a swapped out address space. Most SVCs :>fail with a S0F8 abend if called in AR mode. :>...but not bad. SRB's can be SUSPENDED (not exactly WAIT, but pretty close). If IEAMSCHD is used, the SRB control block need not be created and the WAIT can be automatic. The ECB need not be in CSA - it merely must be HOME addressable from the waiting address space. When using SSAR, take the LOCAL LOCK of the target address space (if the SSAR succeeds). PT(I) sets the primary address space (but be very careful). ALET 0 = primary (hardware) ALET 1 = secondary (hardware) ALET 2 = HOME (DU-AL) The caller of the Basic PC must save the environment. The PC routine (by convention) only restores R13. The caller must save whatever registers as well as the SASN (if needed). Any PC can call any other PC, basic or stacking. They can be hooked, -- Binyamin Dissen <[email protected]> http://www.dissensoftware.com Director, Dissen Software, Bar & Grill - Israel Should you use the mailblocks package and expect a response from me, you should preauthorize the dissensoftware.com domain. I very rarely bother responding to challenge/response systems, especially those from irresponsible companies. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
