Bug#434540: marked as done (MacBook makes subtle whining noise when idle since 2.6.21)
Your message dated Wed, 25 Jul 2007 23:58:52 -0400
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has caused the attached Bug report to be marked as done.
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If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.
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Debian bug tracking system administrator
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--- Begin Message ---
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.
--- End Message ---
--- Begin Message ---
Upon further testing, it seems like the likely cause for this is 2.6.21+ having BETTER power management support - and, thus, entering the lower C-states. I did test disabling tickless operation, and it made the issue worse. I decided to close this because the issue also exists in Mac OS X and the lack of a problem in
2.6.18 seems like an aberration.
--- End Message ---
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