In at least one BIOS that I have worked with the ACPI spec was simply mis-interpreted as needing this flag to be set it to 1 in order to enable ASPM. Seems like a silly mistake but I suspect it is common.
The kernel should probably also be checking to see if the FACS claims to support ACPI 4.0 before relying on this flag.
Posted Jun 30, 2011 17:24 UTC (Thu) by mjg59 (subscriber, #23239)
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Did anyone test that ASPM actually ended up enabled as a result? You're right that the check should be made conditional on the FADT version, though.
PCIe, power management, and problematic BIOSes
Posted Jul 2, 2011 2:05 UTC (Sat) by iceblink (subscriber, #19982)
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Yeah we noticed a spike in power testing and ended up with a DMI workaround until BIOS updates can be rolled out: http://crosbug.com/15124
PCIe, power management, and problematic BIOSes
Posted Jul 2, 2011 3:05 UTC (Sat) by mjg59 (subscriber, #23239)
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Ah, ok, I hadn't realised this was Chrome OS. My concern is more that BIOS vendors in general have this opinion, and Windows handles it differently to us in some way.