diff options
| author | Zhao Yakui <yakui.zhao@intel.com> | 2008-06-24 18:01:09 +0800 |
|---|---|---|
| committer | Andi Kleen <andi@basil.nowhere.org> | 2008-07-16 23:27:05 +0200 |
| commit | da5e09a1b3e5a9fc0b15a3feb64e921ccc55ba74 (patch) | |
| tree | 382a75c1180e458df826ef4efbc191f3f71275c1 /drivers/acpi/processor_idle.c | |
| parent | c1e3b377ad48febba6f91b8ae42c44ee4d4ab45e (diff) | |
ACPI : Create "idle=nomwait" bootparam
"idle=nomwait" disables the use of the MWAIT
instruction from both C1 (C1_FFH) and deeper (C2C3_FFH)
C-states.
When MWAIT is unavailable, the BIOS and OS generally
negotiate to use the HALT instruction for C1,
and use IO accesses for deeper C-states.
This option is useful for power and performance
comparisons, and also to work around BIOS bugs
where broken MWAIT support is advertised.
http://bugzilla.kernel.org/show_bug.cgi?id=10807
http://bugzilla.kernel.org/show_bug.cgi?id=10914
Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Li Shaohua <shaohua.li@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Diffstat (limited to 'drivers/acpi/processor_idle.c')
| -rw-r--r-- | drivers/acpi/processor_idle.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index c75c7ace8c1..d592dbb1d12 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -957,13 +957,17 @@ static int acpi_processor_get_power_info_cst(struct acpi_processor *pr) } else { continue; } - if (cx.type == ACPI_STATE_C1 && idle_halt) { + if (cx.type == ACPI_STATE_C1 && + (idle_halt || idle_nomwait)) { /* * In most cases the C1 space_id obtained from * _CST object is FIXED_HARDWARE access mode. * But when the option of idle=halt is added, * the entry_method type should be changed from * CSTATE_FFH to CSTATE_HALT. + * When the option of idle=nomwait is added, + * the C1 entry_method type should be + * CSTATE_HALT. */ cx.entry_method = ACPI_CSTATE_HALT; snprintf(cx.desc, ACPI_CX_DESC_LEN, "ACPI HLT"); |