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    SubjectIO-APIC in non-SMP mode ?

    Hi,

    I am using a SMP board but I have only 1 CPU inserted. So I have an
    IO-APIC on-board but I am not running my kernel in SMP mode. Right now my
    kernel is not making use of the IO-APIC.

    My understanding is that the IO-APIC allows to schedule interrupts to
    different processors (which I don't need), but is also a lot faster than
    the XT-PIC, thus allowing for much faster handling of interrupts. Is this
    correct ?

    I tried manually inserting CONFIG_X86_IO_APIC=y and
    CONFIG_X86_LOCAL_APIC=y in my .config file and recompiling the kernel just
    to see if it boots, but this highly scientific approach must be flawed
    because it does not compile anyway :) To be more precise, compilation
    fails because FIX_IO_APIC_BASE is undefined, struct mpc_config_intsrc is
    undefined, boot_cpu_id is undefined and cpu_present_map is undefined.

    Would there be any speed advantage to changing the SMP option to be
    YES, NO, or "Uniprocessor on SMP board" with this third option enabling
    the IO-APIC ?

    --
    Michel "Walken" LESPINASSE - Development Engineer at Wind River Systems
    walken@wrs.com - http://www.via.ecp.fr/~walken/
    Microsoft has a Y2K problem. It's called Linux.


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