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authorVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>2006-09-25 19:28:13 -0400
committerLen Brown <len.brown@intel.com>2006-10-14 00:35:39 -0400
commit991528d7348667924176f3e29addea0675298944 (patch)
treeed8552bd4c696700a95ae37b26c4197923207ae7 /include/asm-i386/processor.h
parentb4bd8c66435a8cdf8c90334fb3b517a23ff2ab95 (diff)
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 <venkatesh.pallipadi@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'include/asm-i386/processor.h')
-rw-r--r--include/asm-i386/processor.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/asm-i386/processor.h b/include/asm-i386/processor.h
index 2277127696d2..e0ddca94d50c 100644
--- a/include/asm-i386/processor.h
+++ b/include/asm-i386/processor.h
@@ -306,6 +306,8 @@ static inline void __mwait(unsigned long eax, unsigned long ecx)
306 : :"a" (eax), "c" (ecx)); 306 : :"a" (eax), "c" (ecx));
307} 307}
308 308
309extern void mwait_idle_with_hints(unsigned long eax, unsigned long ecx);
310
309/* from system description table in BIOS. Mostly for MCA use, but 311/* from system description table in BIOS. Mostly for MCA use, but
310others may find it useful. */ 312others may find it useful. */
311extern unsigned int machine_id; 313extern unsigned int machine_id;