Re: PSA 0
Aha! I hadn't thought of the compatibility issue. Thanks. -- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 From: IBM Mainframe Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of Jim Mulder [d10j...@us.ibm.com] Sent: Wednesday, November 24, 2021 8:14 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: PSA 0 0 was the address of the restart new PSW in ESA/390. When we implemented zArchitecture 20 years ago, we set the obsolete ESA/390 interrupt new PSWs such that if someone tried to simulate an interrupt by doing a LPSW for one of them, the result would be a 0E1 wait state with a unique reason code. We figured that after 20 years of that, we had already gotten whatever value that there might have been from that, and it might now be better not to have things like 000A and 000130E1 hanging around down there where some program that has a null pointer bug might pick them up and end up trying to use them as addresses and get into even more weird results or storage overlays (since those are often valid GETMAINed addresses). So in z/OS 2.5, we changed those back to being reserved fields that are initialized to zeroes. Jim Mulder z/OS Diagnosis, Design, Development, Test IBM Corp. Poughkeepsie NY "IBM Mainframe Discussion List" wrote on 11/24/2021 05:58:15 PM: > From: "Hank Oerlemans" <03c4d8bf55f3-dmarc-requ...@listserv.ua.edu> > To: IBM-MAIN@LISTSERV.UA.EDU > Date: 11/24/2021 07:57 PM > Subject: PSA 0 > Sent by: "IBM Mainframe Discussion List" > > A random neuron thinks there was an announcement but if anyone can > shed some light I'm curious about Address 0. > > I am used to seeing X'000A' then X'000130E1' in the first 8-bytes. > This is no longer so. All zeros. A good thing ! > > SA22-7832-12 of Pops doesn't mention anything in CH. 3. > > So was there any kind of announcement for z/OS 2.5 ? -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: PSA 0
We have already discovered this the hard way! We have a C-callable assembler routine to load modules using SVC 8. Its parameter is a C string which is copied into an 8 byte, space-filled area. The loop was terminated by a fragment: CLI 0(R5),0correct BEENDLOOP CLC 0(R5),C' ' wrong!! BEENDLOOP We had been getting away with the typo in the second compare instruction for about the last 25 years; it is actually comparing 5 bytes at address 0 with those at +X'40' and the compare had been failing because the area at +X'40' is all zeros. Come z/OS 2.5 address 0 - 4 is now all zeros, the compare succeeds, the loop terminates immediately and SVC 8 fails with abend S806! I have spent quite a bit of time preparing zaps for product versions going back some years. ☹ Robin -Original Message- From: IBM Mainframe Discussion List On Behalf Of Jim Mulder Sent: 25 November 2021 08:15 To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: PSA 0 0 was the address of the restart new PSW in ESA/390. When we implemented zArchitecture 20 years ago, we set the obsolete ESA/390 interrupt new PSWs such that if someone tried to simulate an interrupt by doing a LPSW for one of them, the result would be a 0E1 wait state with a unique reason code. We figured that after 20 years of that, we had already gotten whatever value that there might have been from that, and it might now be better not to have things like 000A and 000130E1 hanging around down there where some program that has a null pointer bug might pick them up and end up trying to use them as addresses and get into even more weird results or storage overlays (since those are often valid GETMAINed addresses). So in z/OS 2.5, we changed those back to being reserved fields that are initialized to zeroes. Jim Mulder z/OS Diagnosis, Design, Development, Test IBM Corp. Poughkeepsie NY "IBM Mainframe Discussion List" wrote on 11/24/2021 05:58:15 PM: > From: "Hank Oerlemans" > <03c4d8bf55f3-dmarc-requ...@listserv.ua.edu> > To: IBM-MAIN@LISTSERV.UA.EDU > Date: 11/24/2021 07:57 PM > Subject: PSA 0 > Sent by: "IBM Mainframe Discussion List" > > A random neuron thinks there was an announcement but if anyone can > shed some light I'm curious about Address 0. > > I am used to seeing X'000A' then X'000130E1' in the first 8-bytes. > This is no longer so. All zeros. A good thing ! > > SA22-7832-12 of Pops doesn't mention anything in CH. 3. > > So was there any kind of announcement for z/OS 2.5 ? -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: PSA 0
0 was the address of the restart new PSW in ESA/390. When we implemented zArchitecture 20 years ago, we set the obsolete ESA/390 interrupt new PSWs such that if someone tried to simulate an interrupt by doing a LPSW for one of them, the result would be a 0E1 wait state with a unique reason code. We figured that after 20 years of that, we had already gotten whatever value that there might have been from that, and it might now be better not to have things like 000A and 000130E1 hanging around down there where some program that has a null pointer bug might pick them up and end up trying to use them as addresses and get into even more weird results or storage overlays (since those are often valid GETMAINed addresses). So in z/OS 2.5, we changed those back to being reserved fields that are initialized to zeroes. Jim Mulder z/OS Diagnosis, Design, Development, Test IBM Corp. Poughkeepsie NY "IBM Mainframe Discussion List" wrote on 11/24/2021 05:58:15 PM: > From: "Hank Oerlemans" <03c4d8bf55f3-dmarc-requ...@listserv.ua.edu> > To: IBM-MAIN@LISTSERV.UA.EDU > Date: 11/24/2021 07:57 PM > Subject: PSA 0 > Sent by: "IBM Mainframe Discussion List" > > A random neuron thinks there was an announcement but if anyone can > shed some light I'm curious about Address 0. > > I am used to seeing X'000A' then X'000130E1' in the first 8-bytes. > This is no longer so. All zeros. A good thing ! > > SA22-7832-12 of Pops doesn't mention anything in CH. 3. > > So was there any kind of announcement for z/OS 2.5 ? -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: PSA 0
Absolute addresses 0-23 (x'0'-x'17' have an assigned role during IPL; the initial PSW is in 0-7. After that, it whatever the OS puts there. What you're seeing could be a copy of absolute 0-7 after IPL. From: IBM Mainframe Discussion List on behalf of Hank Oerlemans <03c4d8bf55f3-dmarc-requ...@listserv.ua.edu> Sent: Wednesday, November 24, 2021 5:58 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: PSA 0 A random neuron thinks there was an announcement but if anyone can shed some light I'm curious about Address 0. I am used to seeing X'000A' then X'000130E1' in the first 8-bytes. This is no longer so. All zeros. A good thing ! SA22-7832-12 of Pops doesn't mention anything in CH. 3. So was there any kind of announcement for z/OS 2.5 ? Hank -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
PSA 0
A random neuron thinks there was an announcement but if anyone can shed some light I'm curious about Address 0. I am used to seeing X'000A' then X'000130E1' in the first 8-bytes. This is no longer so. All zeros. A good thing ! SA22-7832-12 of Pops doesn't mention anything in CH. 3. So was there any kind of announcement for z/OS 2.5 ? Hank -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
