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    SubjectRe: [PATCH 2.6.24] x86: add sysfs interface for cpuid module
    On Tue, 2008-01-29 at 07:51 -0800, H. Peter Anvin wrote:
    > Yi Yang wrote:
    > > Current cpuid module will create a char device for every logical cpu,
    > > when a user cats /dev/cpu/*/cpuid, he/she will enter a limitless loop,
    > > the root cause is that cpuid module doesn't decide wether a cpuid level
    > > is valid, it just uses an offset to denote cpuid level and take it to
    > > cpuid instruction, cpuid instruction will ignore it and return some data
    > >
    > > This patch uses sysfs to avoid limitless loop and provide more flexible
    > > interface for cpuid, please consider to merge to -mm tree in order to test.
    > This is broken.
    > Triple broken.
    > It's broken, because it doesn't take into account the fact that Intel
    > broke CPUID level 4 and made it "repeating" (neither did the cpuid char
    > device, because it predated the Intel braindamage; I've had a patch for
    > it privately for a while, but didn't push it upstream because paravirt
    > broke it royally and I wanted the situation to settle down.)
    level 4 doesn't result in repeating on Intel CPU, cpuid module sets
    file offset to level, so cat /dev/cpu/*/cpuid will run cpuid instruction

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      Last update: 2008-01-30 08:13    [W:0.021 / U:36.112 seconds]
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