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authorZhao Yakui <yakui.zhao@intel.com>2008-06-17 14:39:59 +0800
committerAndi Kleen <andi@basil.nowhere.org>2008-07-16 23:27:04 +0200
commit5b53496a5ad79e91052f72761a7c5516b069bc99 (patch)
tree2bb559bf2edf363e2b6efa577ca8f2dfd817339d /arch/x86
parent71b58cbb0c30d1f78636a48c4721529449d6ea37 (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')
-rw-r--r--arch/x86/kernel/acpi/processor.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/x86/kernel/acpi/processor.c b/arch/x86/kernel/acpi/processor.c
index de2d2e4ebad9..7c074eec39fb 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;