From: Venkatesh Pallipadi Date: Mon, 25 Sep 2006 23:28:13 +0000 (-0700) Subject: ACPI: Processor native C-states using MWAIT X-Git-Tag: v2.6.20-rc1~179^2~5^2 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=991528d7348667924176f3e29addea0675298944;p=pandora-kernel.git ACPI: Processor native C-states using MWAIT Intel processors starting with the Core Duo support support processor native C-state using the MWAIT instruction. Refer: Intel Architecture Software Developer's Manual http://www.intel.com/design/Pentium4/manuals/253668.htm Platform firmware exports the support for Native C-state to OS using ACPI _PDC and _CST methods. Refer: Intel Processor Vendor-Specific ACPI: Interface Specification http://www.intel.com/technology/iapc/acpi/downloads/302223.htm With Processor Native C-state, we use 'MWAIT' instruction on the processor to enter different C-states (C1, C2, C3). We won't use the special IO ports to enter C-state and no SMM mode etc required to enter C-state. Overall this will mean better C-state support. One major advantage of using MWAIT for all C-states is, with this and "treat interrupt as break event" feature of MWAIT, we can now get accurate timing for the time spent in C1, C2, .. states. Signed-off-by: Venkatesh Pallipadi Signed-off-by: Andrew Morton Signed-off-by: Len Brown --- Reading git-diff-tree failed