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Date: Tue, 14 Nov 2006 10:52:12 -0700 From: ebiederm@...ssion.com (Eric W. Biederman) To: Linus Torvalds <torvalds@...l.org> Cc: Ingo Molnar <mingo@...hat.com>, Komuro <komurojun-mbn@...ty.com>, tglx@...utronix.de, Adrian Bunk <bunk@...sta.de>, Andrew Morton <akpm@...l.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org> Subject: [PATCH] Use delayed disable mode of ioapic edge triggered interrupts Linus Torvalds <torvalds@...l.org> writes: > Of course, for edge-triggered APIC interrupts, we _have_ to replay the irq > (since we don't have any way of even *knowing* whether we might get it > again), but for level-triggered and for the old legacy i8259 controller > that gets it right for edges anwyay, we should _not_ send the spurious > interrupt that is no longer active. > > And a lot of code has been tested with either just the i8259 (old machines > without any APIC) or with PCI-only devices (which are always level- > triggered), so the fact that edge-triggered things have always seen the > potential for spurious interrupts is not a reasong to say "well, they have > to handle it anyway". True PCI drivers generally do _not_ have to handle > the crazy case, and generally have never seen it. > > In other words, I think we should just make APIC-edge have the "please > delay masking and replay" bit, and nobody else. > > Can you send that patch (for both x86 and x86-64), and we can ask Komuro > to test it. That would be the "same behaviour as we've always had" thing, > which I think is also the _right_ behaviour. Hopefully this is the trivial patch that solves the problem. Signed-off-by: Eric W. Biederman <ebiederm@...ssion.com> diff --git a/arch/i386/kernel/io_apic.c b/arch/i386/kernel/io_apic.c index ad84bc2..3b7a63e 100644 --- a/arch/i386/kernel/io_apic.c +++ b/arch/i386/kernel/io_apic.c @@ -1287,9 +1287,11 @@ static void ioapic_register_intr(int irq trigger == IOAPIC_LEVEL) set_irq_chip_and_handler_name(irq, &ioapic_chip, handle_fasteoi_irq, "fasteoi"); - else + else { + irq_desc[irq].status |= IRQ_DELAYED_DISABLE; set_irq_chip_and_handler_name(irq, &ioapic_chip, handle_edge_irq, "edge"); + } set_intr_gate(vector, interrupt[irq]); } diff --git a/arch/x86_64/kernel/io_apic.c b/arch/x86_64/kernel/io_apic.c index 41bfc49..14654e6 100644 --- a/arch/x86_64/kernel/io_apic.c +++ b/arch/x86_64/kernel/io_apic.c @@ -790,9 +790,11 @@ static void ioapic_register_intr(int irq trigger == IOAPIC_LEVEL) set_irq_chip_and_handler_name(irq, &ioapic_chip, handle_fasteoi_irq, "fasteoi"); - else + else { + irq_desc[irq].status |= IRQ_DELAYED_DISABLE; set_irq_chip_and_handler_name(irq, &ioapic_chip, handle_edge_irq, "edge"); + } } static void __init setup_IO_APIC_irqs(void) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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