These patches are against linux-2.6-tip, auto-x86-next. When IRQ lines on secondary or higher IO-APICs are masked (as done by RT and others), many chipsets redirect IRQs on this line to the PIC, and thereby regularly to the first IO-APIC in the system. This causes spurious interrupts and can lead to disabled IRQ lines. Disabling this "boot interrupt" (as it is mostly used to supply all IRQs to the legacy PIC during boot) is chipset-specific, and not possible for all chips. This patchset disables the boot interrupt on chipsets where this is possible and where we know how to do it. When disabling the boot interrupt is not possible, the patches tell the IRQ code to always use the redirected interrupt line (on the first IO-APIC) instead of the "original" line on the secondary (tertiary ...) IO-APIC. The original line remains masked, and IRQs always appear on the boot interrupt line on the first IO-APIC instead. Two new boot parameters control the quirks and are explained in the patches: nobootirqquirk, bootirqquirk=0x,0x,. "noapic" also sets nobootirqquirk. All patches are co-authored by Stefan Assmann and Olaf Dabrunz. But according to Documentation/SubmittingPatches, the patch submission format allows only for one author. drivers/acpi/pci_irq.c | 63 ++++++++ drivers/pci/quirks.c | 339 ++++++++++++++++++++++++++++++++++++++++++++- include/asm-x86/io_apic.h | 4 include/linux/pci.h | 2 include/linux/pci_ids.h | 6 include/linux/pci_quirks.h | 29 +++ 6 files changed, 435 insertions(+), 8 deletions(-) -- Olaf Dabrunz (od/odabrunz), SUSE Linux Products GmbH, Nürnberg