Hi, booting a latest kernel on this machine results in: PCI: PCI BIOS revision 2.10 entry at 0xfd61c, last bus=1 PCI: Using configuration type 1 for base access bio: create slab at 0 ACPI: SCI (IRQ30) allocation failed ACPI Exception: AE_NOT_ACQUIRED, Unable to install System Control Interrupt handler (20090903/evevent-161) ACPI: Unable to start the ACPI Interpreter Later all kind of devices fail... I could bisect it down to this commit: commit b9c61b70075c87a8612624736faf4a2de5b1ed30 Author: Yinghai Lu Date: Wed May 6 10:10:06 2009 -0700 x86/pci: update pirq_enable_irq() to setup io apic routing So we can set io apic routing only when enabling the device irq. This is advantageous for IRQ descriptor allocation affinity: if we set up the IO-APIC entry later, we have a chance to allocate the IRQ descriptor later and know which device it is on and can set affinity accordingly. [ Impact: standardize/enhance irq-enabling sequence for mptable irqs ] Signed-off-by: Yinghai Lu Acked-by: Jesse Barnes Cc: Len Brown Cc: Andrew Morton LKML-Reference: <4A01C46E.8000501@kernel.org> Signed-off-by: Ingo Molnar Attached are dmesg of an umodified broken 2.6.32 kernel and dmesg of a 2.6.32 kernel in which I reverted above patch (apic=verbose). The reverting needed some adjusting and I did this without understanding the code. I also attach the backported patch reverting above for 2.6.32 which makes the machine work again (see dmesg attachment). This probably cannot go in, it would be great if someone could help finding a proper patch for mainline which makes the machine work again. (The ACPI irq, SCI, is meant to be on IRQ 30, rerouted from IRQ 3 via APIC source override table, which is rather odd/uncommon. Hope that helps) Thanks, Thomas