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    Subjectx86_64: How to disable local APIC timer interrupts?
    Hi,

    I am trying to disable the local APIC timer interrupts on x86_64
    machine, but finding that it just doesn't work. I am trying to find out
    if I am doing something wrong or if there is a problem with these CPUs.

    I have a dual-cpu x86_64 machine and I have booted up with 2.6.11 kernel
    and nmi_watchdog=2. I called disable_APIC_timer() function, which seems
    to be setting the 16th bit of the APIC timer register, which is what the
    AMD document suggests to disable the timer. This function is in fact
    __init, but I changed it not to be so. I noticed that we continue to see
    local APIC timer interrupts on the very CPU where I called
    disable_APIC_timer. I have a printk in smp_apic_timer_interrupt() to
    verify this. Booting the machine with maxcpus=1 didn't have any effect
    on the outcome. CPUs are of the following type:

    processor : 0
    vendor_id : AuthenticAMD
    cpu family : 15
    model : 5
    model name : AMD Opteron(tm) Processor 248
    stepping : 8
    cpu MHz : 2193.510
    cache size : 1024 KB
    fpu : yes
    fpu_exception : yes
    cpuid level : 1
    wp : yes
    flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge
    mca cmov pat pse36 clflush mmx fxsr sse sse2 syscall nx mmxext lm
    3dnowext 3dnow
    bogomips : 4325.37
    TLB size : 1088 4K pages
    clflush size : 64
    cache_alignment : 64
    address sizes : 40 bits physical, 48 bits virtual
    power management: ts ttp

    Please let me know if I am doing something wrong and if I should do
    something else to disable local APIC timer interrupts. I need to disable
    these interrupts to solve a problem in LKCD dumping.
    smp_apic_timer_interrupt eventually calls update_process_times, which is
    causing problem in a particular LKCD dump case I am looking at.

    Please copy me on your reply, as I have not subscribed to the list.

    Thanks and regards,
    Sripathi.
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