Hello, When tuning the 2.4.18 kernel, I came across this problem with the IO-APIC setup: IO APIC #2...... .... register #00: 02000000 ....... : physical APIC id: 02 .... register #01: 00178014 ....... : max redirection entries: 0017 ....... : PRQ implemented: 1 ....... : IO APIC version: 0014 WARNING: unexpected IO-APIC, please mail to linux-smp@vger.kernel.org .... register #02: 02000000 ....... : arbitration: 02 I have attached info from dmesg, lspci, and /proc/interrupts to help you out. Thanks for your time, Don Darling