I had been running CentOS 5 happily on my Sun Fire X4200 M2 systems, then I upgraded the BIOS and iLOM firmware. Now I'm running into what seems to be a fairly common problem with newer motherboards. I cannot boot unless I use the 'noapic' kernel option. If I try to boot the kernel normally, I get the error: "MP-BIOS bug: 8254 timer not connected to IO-APIC" I can boot using noapic, but interrupts are *HORRIBLE* with noapic on the X4200 M2. Here is a system with the new BIOS running with noapic: [rordway at aphrodite ~]$ uname -a Linux aphrodite 2.6.18-53.1.4.el5.centos.plus #1 SMP Fri Dec 7 07:05:12 EST 2007 x86_64 x86_64 x86_64 GNU/Linux [rordway at aphrodite ~]$ cat /proc/interrupts CPU0 CPU1 CPU2 CPU3 0: 149047419 568805 215848 76392 XT-PIC timer 1: 0 2 0 0 XT-PIC i8042 2: 0 0 0 0 XT-PIC cascade 4: 399 80 58 26 XT-PIC serial 5: 138 19 4 4 XT-PIC ehci_hcd:usb2 7: 16203243 179851060 180334480 180522274 XT-PIC ioc0, eth1 8: 1 0 0 0 XT-PIC rtc 9: 0 0 0 0 XT-PIC acpi 11: 764 64 17 21 XT-PIC ohci_hcd:usb1 12: 2 2 0 0 XT-PIC i8042 14: 77 6 13 3 XT-PIC ide0 15: 15353489 192264 58884 10141 XT-PIC eth0 NMI: 0 0 0 0 LOC: 149884909 149891944 149889634 149890602 ERR: 377601098 MIS: 0 Compare this to an identical system running an identical kernel, but the older BIOS: [rordway at selene ~]$ uname -a Linux selene 2.6.18-53.1.4.el5.centos.plus #1 SMP Fri Dec 7 07:05:12 EST 2007 x86_64 x86_64 x86_64 GNU/Linux [rordway at selene ~]$ cat /proc/interrupts CPU0 CPU1 CPU2 CPU3 0: 415472769 0 0 0 IO-APIC-edge timer 1: 2 0 0 0 IO-APIC-edge i8042 4: 270 0 10 17 IO-APIC-edge serial 8: 1 0 0 0 IO-APIC-edge rtc 9: 0 0 0 0 IO-APIC-level acpi 12: 4 0 0 0 IO-APIC-edge i8042 14: 25 74 0 0 IO-APIC-edge ide0 58: 323 464 0 0 IO-APIC-level ohci_hcd:usb1 66: 26 0 0 0 IO-APIC-level ehci_hcd:usb2 74: 5940 981922 7254 524 IO-APIC-level ioc0 82: 2026 53828037 0 138601 IO-APIC-level eth0 90: 2237 61820570 0 689058 IO-APIC-level eth1 NMI: 0 0 0 0 LOC: 415433007 415433000 415432928 415432856 ERR: 0 MIS: 0 Note the huge ERR count with XT-APIC, and ioc0 and eth1 sharing an interrupt (SAS controller and my private network interface) Does anyone know if this has been fixed in the mainline kernel, and if so if this can be integrated into the CentOS 5.1 kernel (namely the CentOS Plus kernel)? Thanks! Ryan -- Ryan Ordway E-mail: rordway at oregonstate.edu Unix Systems Administrator rordway at library.oregonstate.edu OSU Libraries, Corvallis, OR 97331 Office: Valley Library #4657