On Thu, 5 Sep 2019 04:39:12 -0500, Sebastian Welton wrote: >A colleague of mine has been developing an MPF exit which calls System REXX but this seems to have thrown up a weird type of error.
>The program compiles fine That is irrelevant. >upon the first two invocations of the exit a S0C4 with reason code 11 >abend occurs but after reactivating the exit again, it all works fine. It is very unlikely that it works fine. More likely the S0C4 did not occur because the code was "lucky" enough to have addressed storage that had been allocated by some program, and it likely clobbered that storage. >Neither of us is an experienced assembler programmer but looking >through the code it seems fine: It is not "fine". A programming error caused S0C4 abends due to referencing unallocated storage and attempting to modify it. MPF exits receive control in key 0 Supervisor state. Frankly, an inexperienced assembler programmer with limited, if any, debugging experience should not be writing such code. >Time of Error Information > PSW: 07041000 80000000 00000000 1ECDE102 > Instruction length: 06 Interrupt code: 0011 > Failing instruction text: 60224110 D088D7D7 10001000 > Translation exception address: 00000000_1F701800 > Breaking event address: 00000000_1ECDE05E This gives a clue. The failing instruction was D7D710001000 to clear storage pointed to by register 1 for a length of 216 bytes. Register 1 may be pointing to offset X'88' after the address in register 13. Either the address or the length is wrong. Or both. >we're going on the possibility that the error lies elsewhere. The error is in your (or your colleague's) program. >Any pointers, hints or tips would be gratefully accepted. Do not implement this exit on any system that you care about. If you want an MPF exit, or any other system exit, you need to find someone with experience writing and debugging key zero supervisor state code. -- Tom Marchant ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
