Messages in this thread Patch in this message | | | From | (Joe Korty) | Subject | [RFC][PATCH] irq0 affinity broke on some i386 boxes | Date | Mon, 25 Feb 2002 13:56:51 -0500 (EST) |
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Hi everyone, The following patch fixes a bug that prevents a write to /proc/irq/0/smp_affinity from actually changing the cpu affinity of IRQ #0, on all the (Dell server) SMP machines I have access to.
Given the wide variety of IO APIC and legacy PIC usage on various SMP motherboards, and the nascent state of my APIC understanding, it is quite likely that this fix is not universal.
I would like expand this patch so that IRQ0 affinity assignment works properly on as many i386 SMP motherboards as possible. If you have such a motherboard, please first 1) verify that assignments to /proc/irq/0/smp_affinity NOP for you, and 2) if it does NOP, that this patch does or does not fix the problem on your system.
To verify that your system has the problem or not:
in one window, run `watch -n1 cat /proc/interrupts'.
in another window, assign some affinity value to irq0. In the following example, cpu #0 (in a 4-cpu system) is to no longer get irq0 interrupts:
echo e >/proc/irq/0/smp_affinity
If your system is working properly, the watch-window should no longer show increments for the irq0 value for cpu0.
This patch is against 2.4.18-rc4
Joe
--- linux/arch/i386/kernel/io_apic.c.orig Tue Nov 13 20:28:41 2001 +++ linux/arch/i386/kernel/io_apic.c Mon Feb 25 13:17:13 2002 @@ -1537,6 +1537,7 @@ setup_nmi(); check_nmi_watchdog(); } + add_pin_to_irq(0, 0, pin2); return; } /* - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.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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