Subject:[ACPI]:Add module parameter processor.idle to disable mwait for CPU C-states From: Zhao Yakui <yakui.zhao@xxxxxxxxx> Add the module parameter processor.idle to disable Mwait for CPU C-states. If the module parameter of "processor.idle=1" is added , OSPM should not use mwait for cpu idle even when the mwait is supported. In such case the C2C3_FFH access mode will be disabled. http://bugzilla.kernel.org/show_bug.cgi?id=10807 Signed-off-by: Zhao Yakui <yakui.zhao@xxxxxxxxx> Signed-off-by: Li Shaohua <shaohua.li@xxxxxxxxx> --- Documentation/kernel-parameters.txt | 4 ++++ drivers/acpi/processor_core.c | 16 +++++++++++++++- 2 files changed, 19 insertions(+), 1 deletion(-) Index: linux-2.6/drivers/acpi/processor_core.c =================================================================== --- linux-2.6.orig/drivers/acpi/processor_core.c +++ linux-2.6/drivers/acpi/processor_core.c @@ -79,6 +79,10 @@ MODULE_AUTHOR("Paul Diefenbaugh"); MODULE_DESCRIPTION("ACPI Processor Driver"); MODULE_LICENSE("GPL"); +static int idle_nomwait; +module_param_named(idle, idle_nomwait, int, 0); +MODULE_PARM_DESC(idle, "Disable the mwait for CPU idle"); + static int acpi_processor_add(struct acpi_device *device); static int acpi_processor_start(struct acpi_device *device); static int acpi_processor_remove(struct acpi_device *device, int type); @@ -261,11 +265,21 @@ static int acpi_processor_set_pdc(struct { struct acpi_object_list *pdc_in = pr->pdc; acpi_status status = AE_OK; + u32 *buffer = NULL; + union acpi_object *obj; if (!pdc_in) return status; - + if (idle_nomwait) { + /* + * If mwait is not used for cpu C-states, the C2C3_FFH + * will be disabled in the paramter of _PDC object. + */ + obj = pdc_in->pointer; + buffer = (u32 *) (obj->buffer.pointer); + buffer[2] &= ~ACPI_PDC_C_C2C3_FFH; + } status = acpi_evaluate_object(pr->handle, "_PDC", pdc_in, NULL); if (ACPI_FAILURE(status)) Index: linux-2.6/Documentation/kernel-parameters.txt =================================================================== --- linux-2.6.orig/Documentation/kernel-parameters.txt +++ linux-2.6/Documentation/kernel-parameters.txt @@ -1617,6 +1617,10 @@ and is between 256 and 4096 characters. Ignore the _CST method to determine C-states, instead using the legacy FADT method + processor.idle= [HW,ACPI] + { 1 } disable MWait for CPU C-states even when MWAIT + is supported + prompt_ramdisk= [RAM] List of RAM disks to prompt for floppy disk before loading. See Documentation/ramdisk.txt. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
