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On Thu, 5 May 2005, Len Brown wrote: > Re: SMP using i8259> While Linux in ACPI mode allows "noapic" on SMP, it isn't recommended. > It is there for comparisons, debugging, and to work-around the odd > broken system. It is an exception configuration, and supporting it > should in no way impact the design for other 99.99% normal systems. > > Indeed, note that SMP systems using i8259 instead of IOAPIC > is explicity forbidden by MPS, and thus would probably fail > the compatibility test for your favorite high volume binary OS. I'm not quite sure if that's forbidden by MPS -- the mixed mode certainly is not as not all interrupt sources may necessarily be routed to one of I/O APICs, and "noapic" can probably be treated as a special case of the mixed mode. Regardless, there used to be systems in existence that wouldn't route IRQ 0 to an I/O APIC, so using that interrupt requires either the mixed mode or using the "through-i8259A" trick (which unfortunately does not work for a subset of affected systems as a result of manufacturers implementing the Intel-recommended glue logic at the output of the master i8259). Maciej - 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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