Interesting. I wonder if "future supervisor function" may include the actual ability to USE the various TRAP-related instructions defined in the z architecture in application-level (problem state) code running in z/OS.
That would be really nice. At least some application developers out here in the wild have been waiting a long time already for that capability. It's a bit frustrating to have a potentially useful architectural capability not supported by the OS you run under. Peter -----Original Message----- From: IBM Mainframe Discussion List <[email protected]> On Behalf Of David Cole Sent: Friday, August 7, 2020 2:32 PM To: [email protected] Subject: Re: Discrepancy regarding the real address of the DUCT Thanks Rob. That's pretty much what I was guessing. -Dave At 8/7/2020 11:43 AM, Rob Scott wrote: >Dave >The change in IHASTCB log refers to APAR OA54589 which indicates >"support for future supervisor function". >I am guessing we are not quite in the future enough yet. >Rob > > >>From: IBM Mainframe Discussion List <[email protected]> On >>Behalf Of David Cole >>Sent: Friday, August 7, 2020 12:10 PM >>To: [email protected] >>Subject: Discrepancy regarding the real address of the DUCT EXTERNAL >>EMAIL >> >> >>I was researching the disappearance of an STCB field (STCBDUCR) in >>z/OS R2.4 maclibs when I noticed a discrepancy that has me puzzled: >>1) Up until zOS R2.3, the STCBDUCR field used to contain the 31-bit >>REAL address of the Dispatchable Unit Control Table (DUCT). >>2) But in the z/OS R2.4 maclibs, in the STCB mapping macro (IHASTCB), >>the STCBDUCR field was removed, and a new 64-bit field was added: >>STCBDCR8. This is caption as "Real address of the DUCT". >>3) When a DUCT is active, it's real address is carried in Control >>Register 2 ("CR2"). So I went to the -12 edition of Principles (new >>with advent of the Z15 machine) to see if the definition of CR2 had changed. >>4) To my surprise, it had not! >>- It still describes the DUCTO as... "Bits 33-57 of control register >>2, with six zeros appended on the right, form a 31-bit real address >>that designates the beginning of the dispatchable- unit control >>table". >>- And it still shows bits 0 thru 32 of CR2 as being reserved! >> >>So the discrepancy is this: >>- The STCB has been prepared to hold an 8-byte wide real address of >>the DUCT. >>- Yet the hardware (i.e. CR2) still only supports a 31-bit real address! >> >> >>Can anyone shed some light on this? >> >>TIA >>Dave Cole -- This message and any attachments are intended only for the use of the addressee and may contain information that is privileged and confidential. If the reader of the message is not the intended recipient or an authorized representative of the intended recipient, you are hereby notified that any dissemination of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by e-mail and delete the message and any attachments from your system. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
