diff options
| author | Zhao Yakui <yakui.zhao@intel.com> | 2008-06-24 17:58:53 +0800 |
|---|---|---|
| committer | Andi Kleen <andi@basil.nowhere.org> | 2008-07-16 23:27:05 +0200 |
| commit | c1e3b377ad48febba6f91b8ae42c44ee4d4ab45e (patch) | |
| tree | 7893e4226f52c4001150066f544415c1b17741f5 /arch | |
| parent | 5b53496a5ad79e91052f72761a7c5516b069bc99 (diff) | |
ACPI: Create "idle=halt" bootparam
"idle=halt" limits the idle loop to using
the halt instruction. No MWAIT, no IO accesses,
no C-states deeper than C1.
If something is broken in the idle code,
"idle=halt" is a less severe workaround
than "idle=poll" which disables all power savings.
Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/ia64/kernel/process.c | 2 | ||||
| -rw-r--r-- | arch/x86/kernel/process.c | 17 |
2 files changed, 18 insertions, 1 deletions
diff --git a/arch/ia64/kernel/process.c b/arch/ia64/kernel/process.c index fabaf08d9a69..612b3c4a0603 100644 --- a/arch/ia64/kernel/process.c +++ b/arch/ia64/kernel/process.c @@ -55,6 +55,8 @@ void (*ia64_mark_idle)(int); unsigned long boot_option_idle_override = 0; EXPORT_SYMBOL(boot_option_idle_override); +unsigned long idle_halt; +EXPORT_SYMBOL(idle_halt); void ia64_do_show_stack (struct unw_frame_info *info, void *arg) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 7dceea947232..7fc729498760 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -7,6 +7,10 @@ #include <linux/module.h> #include <linux/pm.h> #include <linux/clockchips.h> +#include <asm/system.h> + +unsigned long idle_halt; +EXPORT_SYMBOL(idle_halt); struct kmem_cache *task_xstate_cachep; @@ -325,7 +329,18 @@ static int __init idle_setup(char *str) pm_idle = poll_idle; } else if (!strcmp(str, "mwait")) force_mwait = 1; - else + else if (!strcmp(str, "halt")) { + /* + * When the boot option of idle=halt is added, halt is + * forced to be used for CPU idle. In such case CPU C2/C3 + * won't be used again. + * To continue to load the CPU idle driver, don't touch + * the boot_option_idle_override. + */ + pm_idle = default_idle; + idle_halt = 1; + return 0; + } else return -1; boot_option_idle_override = 1; |