Linked by Mike on Fri 11th Nov 2011 18:40 UTC
Linux "At long last, it looks like there is an adequate solution to the Active State Power Management (ASPM) problem in the Linux kernel , a.k.a. the well-known and wide-spread power regression in the Linux 2.6.38 kernel, which has been causing many laptops to go through significantly more power than they should. This is not another workaround, but rather a behavioral change in the kernel to better decide when the PCI Express ASPM support should be toggled."
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RE: Surprising
by mjg59 on Fri 11th Nov 2011 21:09 UTC in reply to "Surprising"
mjg59
Member since:
2005-10-17

The mistake you're making here is to assume that there's any external documentation at all. _OSC is well defined, but the precise semantics of how hardware vendors expect it to work isn't. The FADT bit is moderately well defined, but again the precise semantics of how hardware vendors expect it to work isn't. ASPM itself is well defined, but... you get the picture. And often even the hardware vendors don't really know how it all works, they just know that they configured a machine in a specific way with a specific set of firmware configuration options and everything worked as they expected when they booted Windows.

The only really important specification here is how Windows behaves, and I doubt that's documented anywhere other than the Windows source code. So we're left trying to infer how things are meant to work by a combination of trying different things until something seems to work for everyone.

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