forked from Minki/linux
ca1b940ce6
When PM-Timer is available for local APIC timer calibration we can skip the verification of the calibrated time value. The resulting error is quite small on a bunch of evaluated platforms and is less harming than the observed false positives. We need to keep the verification on systems, which have no PM-Timer to avoid bogus local APIC timer calibrations in the range of factor 2-10, which can be observed when swicthing off the PM-timer support in the kernel configuration. The wrong calibration values are probably caused by SMM code trying to emulate a PS/2 keyboard from a (maybe connected or not) USB keyboard. This prohibits the accurate delivery of PIT interrupts, which are used to calibrate the local APIC timer. Unfortunately we have no way to disable this BIOS misfeature in the early boot process. Add also the dropped cpu_relax() back to the wait loops. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Ingo Molnar <mingo@elte.hu> Acked-by: Andi Kleen <ak@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
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