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    SubjectRe: [KVM timekeeping 13/35] Perform hardware_enable in CPU_STARTING callback
    On 08/27/2010 06:32 AM, Jan Kiszka wrote:
    > Zachary Amsden wrote:
    >
    >> The CPU_STARTING callback was added upstream with the intention
    >> of being used for KVM, specifically for the hardware enablement
    >> that must be done before we can run in hardware virt. It had
    >> bugs on the x86_64 architecture at the time, where it was called
    >> after CPU_ONLINE. The arches have since merged and the bug is
    >> gone.
    >>
    > What bugs are you referring to, or since which kernel version is
    > CPU_STARTING usable for KVM? I need to encode this into kvm-kmod.
    >

    Prior to the x86_64 / i386 merge, CPU_STARTING didn't work the same way
    / exist in the x86_64 code... most of this is historical guesswork. At
    some point, the 32/64 versions of the code in smpboot.c got merged and
    now it does.

    Binary searching around my tree shows this timeframe:

    2.6.11? - 2.6.23 : silver age ; i386 and x86_64 merge underway
    |
    2.6.24 : bronze age ; i386 and x86_64 deprecated
    |
    2.6.26 : iron age; smpboot_32.c / smpboot_64.c merge
    \
    2.6.28 : CPU_STARTING exists and first used

    /me scratches head wondering how this affects operation on older kernels....


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