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-ia64/processor.h b/include/asm-ia64/processor.h
index 6aff126fc07e..f36e28a5f61e 100644
--- a/include/asm-ia64/processor.h
+++ b/include/asm-ia64/processor.h
@@ -763,6 +763,7 @@ prefetchw (const void *x)
 #define spin_lock_prefetch(x)   prefetchw(x)
 
 extern unsigned long boot_option_idle_override;
+extern unsigned long idle_halt;
 
 #endif /* !__ASSEMBLY__ */