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    SubjectRe: [PATCH 2/9] x86 idle: remove NOP cpuinfo_x86.hlt_works_ok flag
    On 03/31/2011 07:41 AM, Alan Cox wrote:
    >>
    >> What it was was bad power supplies or low-capacitance, high-inductance
    >> power distribution that happened to work with MS-DOS which always burned
    >> the CPU at 100% and therefore left the power draw relatively consistent
    >> current. A proper OS putting the CPU in HLT produced a lot more high
    >> frequency noise on the power busses, with disastrous results without
    >> proper bypass.
    >
    > And also chipset errata in some cases - eg some revisions of the CS5510
    > hung the box solid if a CPU hlt occurred during an IDE transfer. I don't
    > think any CS5510s are still around although I've had mail from someone
    > with a CS5520 in use not that long ago so who knows!
    >
    > The joy of ancient history.

    Ah, yes, I guess there was a special cycle on the bus which the chipset
    could misinterpret.

    -hpa

    --
    H. Peter Anvin, Intel Open Source Technology Center
    I work for Intel. I don't speak on their behalf.



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