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    SubjectRe: [BUG] x86 kenel won't boot under Virtual PC
    Ingo Molnar wrote:
    > yes. X86_P6_NOPS is a totally insignificant optimization and if it makes
    > _any_ CPU not boot (be that virtual or real), then it's frankly not
    > worth it.
    > David, exactly how does the kernel fail to boot with latest -git?
    > (v2.6.27-rc5-313-g64f996f or later) Does detect_nopl() run? It really
    > should, and it should detect the non-working instructions.

    Okay, a few things here...

    1. First, I wrote up a patch yesterday to update the CONFIG_X86_GENERIC
    description and to make it "default y". It is currently on
    x86/defconfig, but I think it should be promoted to mainline immediately.

    2. X86_P6_NOPS is not the only source of static NOPLs. If gcc is set to
    optimize for specific architectures, then gcc/binutils will generate
    static NOPLs. The only way we can prevent that is by not using specific
    -march options, as far as I can tell.

    3. I'm not positive that CONFIG_X86_GENERIC currently avoid all cases of
    (2), but it obviously should. I will verify that today and add a
    followup patch to the Makefiles if necessary.

    Given all of this, I really think that putting this on
    CONFIG_X86_GENERIC, *AND* making CONFIG_X86_GENERIC the default is the
    right choice.


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      Last update: 2008-09-08 17:41    [W:0.020 / U:6.588 seconds]
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