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>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/asm-x86/processor.h b/include/asm-x86/processor.h
index 7f7382704592..bc221623248e 100644
--- a/include/asm-x86/processor.h
+++ b/include/asm-x86/processor.h
@@ -727,6 +727,7 @@ extern int			force_mwait;
 extern void select_idle_routine(const struct cpuinfo_x86 *c);
 
 extern unsigned long            boot_option_idle_override;
+extern unsigned long            idle_halt;
 
 extern void enable_sep_cpu(void);
 extern int sysenter_setup(void);