[Techtalk] Spurious kernel interrupt?

Alain Tesio alain at onesite.org
Thu Aug 29 23:04:57 EST 2002

On Thu, 29 Aug 2002 16:39:08 -0400
Terri Oda <terri at zone12.com> wrote:

> Aug 29 16:25:09 ostraya kernel: spurious 8259A interrupt: IRQ7.

In the kernel sources, file /arch/i386/kernel/i8259.c, it's described
as "hardware problems".

The conditional defines CONFIG_SMP and CONFIG_X86_LOCAL_APIC
are used in this file, maybe you have a kernel configured for SMP and a
system with only one processor ?


	spin_lock_irqsave(&i8259A_lock, flags);
	 * Lightweight spurious IRQ detection. We do not want
	 * to overdo spurious IRQ handling - it's usually a sign
	 * of hardware problems, so we only do the checks we can
	 * do without slowing down good hardware unnecesserily.
	 * Note that IRQ7 and IRQ15 (the two spurious IRQs
	 * usually resulting from the 8259A-1|2 PICs) occur
	 * even if the IRQ is masked in the 8259A. Thus we
	 * can check spurious 8259A IRQs without doing the
	 * quite slow i8259A_irq_real() call for every IRQ.
	 * This does not cover 100% of spurious interrupts,
	 * but should be enough to warn the user that there
	 * is something bad going on ...
	if (cached_irq_mask & irqmask)
		goto spurious_8259A_irq;
	cached_irq_mask |= irqmask;

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