diff options
| author | Zhao Yakui <yakui.zhao@intel.com> | 2008-06-17 14:39:59 +0800 |
|---|---|---|
| committer | Andi Kleen <andi@basil.nowhere.org> | 2008-07-16 23:27:04 +0200 |
| commit | 5b53496a5ad79e91052f72761a7c5516b069bc99 (patch) | |
| tree | 2bb559bf2edf363e2b6efa577ca8f2dfd817339d /arch/x86/kernel | |
| parent | 71b58cbb0c30d1f78636a48c4721529449d6ea37 (diff) | |
ACPI: Disable the C2C3_FFH access mode HW has no MWAIT support
991528d7348667924176f3e29addea0675298944
(ACPI: Processor native C-states using MWAIT)
started passing C2C3_FFH to _PDC to tell the BIOS
that Linux supports MWAIT for deep C-states.
However, we should first double check with the hardware
that it actually supports MWAIT before potentially exposing
a BIOS bug of an MWAIT _CST on HW that doesn't support MWAIT.
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 'arch/x86/kernel')
| -rw-r--r-- | arch/x86/kernel/acpi/processor.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/x86/kernel/acpi/processor.c b/arch/x86/kernel/acpi/processor.c index de2d2e4ebad..7c074eec39f 100644 --- a/arch/x86/kernel/acpi/processor.c +++ b/arch/x86/kernel/acpi/processor.c @@ -56,6 +56,12 @@ static void init_intel_pdc(struct acpi_processor *pr, struct cpuinfo_x86 *c) if (cpu_has(c, X86_FEATURE_ACPI)) buf[2] |= ACPI_PDC_T_FFH; + /* + * If mwait/monitor is unsupported, C2/C3_FFH will be disabled + */ + if (!cpu_has(c, X86_FEATURE_MWAIT)) + buf[2] &= ~(ACPI_PDC_C_C2C3_FFH); + obj->type = ACPI_TYPE_BUFFER; obj->buffer.length = 12; obj->buffer.pointer = (u8 *) buf; |