diff options
| author | Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> | 2006-09-25 16:28:13 -0700 |
|---|---|---|
| committer | Len Brown <len.brown@intel.com> | 2006-10-14 00:35:39 -0400 |
| commit | 991528d7348667924176f3e29addea0675298944 (patch) | |
| tree | ed8552bd4c696700a95ae37b26c4197923207ae7 /include/asm-i386 | |
| parent | b4bd8c66435a8cdf8c90334fb3b517a23ff2ab95 (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')
| -rw-r--r-- | include/asm-i386/processor.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/asm-i386/processor.h b/include/asm-i386/processor.h index 2277127696d..e0ddca94d50 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) : :"a" (eax), "c" (ecx)); } +extern void mwait_idle_with_hints(unsigned long eax, unsigned long ecx); + /* from system description table in BIOS. Mostly for MCA use, but others may find it useful. */ extern unsigned int machine_id; |