Bug#434540: MacBook makes subtle whining noise when idle since 2.6.21
Package: linux-image-2.6-686
Version: 2.6.22-1
Since kernel 2.6.21, my MacBook has made a subtle whining noise when idle. This happens when using the Debian stock kernels from testing and unstable, but also when using other kernels. I believe it has something to do with certain ACPI power-saving modes and/or the switch from 250hz kernel timing to a tickless kernel.
2.6.18 as shipped in Etch does NOT exhibit this problem, and disabling C3/C4 ACPI C-states is a functional workaround for 2.6.21+ (though doing so results in the loss of some battery life). However, C3/C4 ACPI C-states work fine in the aforementioned
2.6.18 kernel, so the HZ timing seems like a more likely root cause.
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