In a message dated 10/26/2006 11:06:49 A.M. Central Daylight Time, [EMAIL PROTECTED] writes:
>In MVT days (i.e. pre-DAT days) Type-3 and Type-4 SVCs (and I think >certain machine check error handling routines, but I'm not sure) were >loaded into a fixed set of 1K buffers. As interrupts would occur, the >SVC code (if any) being used by the interrupted task would be >overlayed in the buffers by SVC code (if any) being used by the >interrupting task. It definitely worked that way for machine check interrupts under MFT. I spent two consultant days figuring out why a model 40 MFT system crashed intermittently. Customer had applied maintenance, the newer version of one SVC module involved in MCH was slightly longer than 1K, a machine check occurred, the extra few bytes overlaid a few instructions in the next higher 1K buffer, and at some unpredictable time later that next buffer's module was used for some SVC function which crashed the system. Bill Fairchild ---------------------------------------------------------------------- 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
