Il 03/09/2012 12:34, Jan Kiszka ha scritto: >> > Why is this a problem? All of them use IRQ2 for a cascade, and initialize >> > icw3 to 0x4/0x2 (I checked OpenBIOS, rth's palcode for Alpha, and Linux). > IRQ2 is already hard-coded in QEMU (we had to patch this for our machine > emulation, but less in recent versions), that is not the point. I'm > concerned about the behavioral changes we are discussing here, ie. the > special handling of cascading interrupt inputs.
Yeah, it's quite interesting that the behavior isn't mentioned in the 8259 datasheets. Still in retrospect it's hard to see how it can possibly work with edge-triggered cascaded inputs. Paolo
