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 continuously.
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