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    SubjectRe: SMP broken on pre-ACPI machine.
    On Wednesday 18 October 2006 18:24, Dave Jones wrote:
    > I've been chasing a bug that got filed against the Fedora kernel
    > a while back:
    > This is a dual pentium pro from an era before we had ACPI, and
    > it seems to be falling foul of this test in smpboot.c ..
    > if (!smp_found_config && !acpi_lapic) {
    > printk(KERN_NOTICE "SMP motherboard not detected.\n");
    > smpboot_clear_io_apic_irqs();
    > phys_cpu_present_map = physid_mask_of_physid(0);
    > if (APIC_init_uniprocessor())
    > printk(KERN_NOTICE "Local APIC not detected."
    > " Using dummy APIC emulation.\n");
    > map_cpu_to_logical_apicid();
    > cpu_set(0, cpu_sibling_map[0]);
    > cpu_set(0, cpu_core_map[0]);
    > return;
    > }
    > My initial reaction is that the !acpi_lapic test should be conditional
    > on some variable that gets set if the ACPI parsing actually succeeded.

    acpi_lapic isn't related to the problem at hand -- that smp_found_config is not set.

    That said, allowing acpi_lapic=1 to bail out of this check has the sole
    function of allowing SMP/PIC configurations. (smp_found_config
    in ACPI mode is set if acpi_lapic and acpi_ioapic are set)
    SMP/PIC configurations are not very interesting, except for debugging.
    Indeed, MPS prohibits them by mandating an IOAPIC be present for SMP --
    but ACPI has no such rule.

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      Last update: 2006-10-19 07:33    [W:0.024 / U:35.868 seconds]
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