Hi, there seems to by an off-by-one error in Io_apic::find_apic() that kills IRQ-routing for GSIs that are a multiple of 24. Please consider the patch below (tested on real hardware with 3 IO-APICS). regards Christian diff --git a/src/kernel/fiasco/src/kern/io_apic.cpp b/src/kernel/fiasco/src/kern/io_apic.cpp index 88ffe68..897a1a0 100644 --- a/src/kernel/fiasco/src/kern/io_apic.cpp +++ b/src/kernel/fiasco/src/kern/io_apic.cpp @@ -331,7 +331,7 @@ Io_apic::find_apic(unsigned irqnum) { for (unsigned i = Max_ioapics; i > 0; --i) { - if (_apics[i-1]._apic && _apics[i-1]._offset < irqnum) + if (_apics[i-1]._apic && _apics[i-1]._offset <= irqnum) return i - 1; } return 0;