# HG changeset patch
# User root@xxxxxxxxxxxxxxxxxxxxx
# Date 1167751141 -19800
# Node ID 7b571c2e65eb86e73f7a2c8cb67e8acb2d129d82
# Parent  711c31232d71608fe4ea9f4f22ca2620d3faf8ff
Added support for idle=poll kernel option.

Signed-off-by: Amitabha Roy <amitabha.roy@xxxxxxxxx>

diff -r 711c31232d71 -r 7b571c2e65eb linux-2.6-xen-sparse/arch/i386/kernel/process-xen.c
--- a/linux-2.6-xen-sparse/arch/i386/kernel/process-xen.c	Tue Jan 02 10:57:50 2007 +0000
+++ b/linux-2.6-xen-sparse/arch/i386/kernel/process-xen.c	Tue Jan 02 20:49:01 2007 +0530
@@ -101,7 +101,21 @@ void enable_hlt(void)
 
 EXPORT_SYMBOL(enable_hlt);
 
-/* XXX XEN doesn't use default_idle(), poll_idle(). Use xen_idle() instead. */
+/* Xen will use either  xen_idle() or poll_idle() */
+static void poll_idle(void)
+{
+	local_irq_enable();
+
+	asm volatile(
+		"2:"
+		"testl %0, %1;"
+		"rep; nop;"
+		"je 2b;"
+		: : "i"(_TIF_NEED_RESCHED), "m" (current_thread_info()->flags));
+}
+
+
+
 void xen_idle(void)
 {
 	local_irq_disable();
@@ -162,7 +176,7 @@ void cpu_idle(void)
 				play_dead();
 
 			__get_cpu_var(irq_stat).idle_timestamp = jiffies;
-			xen_idle();
+			pm_idle();
 		}
 		preempt_enable_no_resched();
 		schedule();
@@ -198,9 +212,28 @@ void cpu_idle_wait(void)
 }
 EXPORT_SYMBOL_GPL(cpu_idle_wait);
 
-/* XXX XEN doesn't use mwait_idle(), select_idle_routine(), idle_setup(). */
-/* Always use xen_idle() instead. */
-void __devinit select_idle_routine(const struct cpuinfo_x86 *c) {}
+/* XEN does idle_setup() to decide if the kernel should poll or call into 
+ * the hypervisor when it has nothing else to do
+.*/
+
+static int __init idle_setup (char * str){
+  if(!strncmp(str,"poll",4)){
+    printk("Using polling idle threads. \n");
+    pm_idle=poll_idle;
+  }
+  else{
+    pm_idle=xen_idle;
+  }
+  return 1;
+}
+
+__setup("idle=", idle_setup);
+
+void __devinit select_idle_routine(const struct cpuinfo_x86 *c) {
+	if(!pm_idle){
+	  pm_idle=xen_idle;
+	}
+}
 
 void show_regs(struct pt_regs * regs)
 {
diff -r 711c31232d71 -r 7b571c2e65eb linux-2.6-xen-sparse/arch/x86_64/kernel/process-xen.c
--- a/linux-2.6-xen-sparse/arch/x86_64/kernel/process-xen.c	Tue Jan 02 10:57:50 2007 +0000
+++ b/linux-2.6-xen-sparse/arch/x86_64/kernel/process-xen.c	Tue Jan 02 20:49:01 2007 +0530
@@ -119,7 +119,22 @@ void exit_idle(void)
 	__exit_idle();
 }
 
-/* XXX XEN doesn't use default_idle(), poll_idle(). Use xen_idle() instead. */
+/* Xen will use either  xen_idle() or poll_idle() */
+
+static void poll_idle (void)
+{
+	local_irq_enable();
+
+	asm volatile(
+		"2:"
+		"testl %0,%1;"
+		"rep; nop;"
+		"je 2b;"
+		: :
+		"i" (_TIF_NEED_RESCHED),
+		"m" (current_thread_info()->flags));
+}
+
 void xen_idle(void)
 {
 	local_irq_disable();
@@ -171,7 +186,7 @@ void cpu_idle (void)
 			if (cpu_is_offline(smp_processor_id()))
 				play_dead();
 			enter_idle();
-			xen_idle();
+			pm_idle();
 			__exit_idle();
 		}
 
@@ -210,9 +225,28 @@ void cpu_idle_wait(void)
 }
 EXPORT_SYMBOL_GPL(cpu_idle_wait);
 
-/* XXX XEN doesn't use mwait_idle(), select_idle_routine(), idle_setup(). */
-/* Always use xen_idle() instead. */
-void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c) {}
+void __cpuinit select_idle_routine(const struct cpuinfo_x86 *c) 
+{
+  if (!pm_idle){
+    pm_idle=xen_idle;
+  }
+}
+
+static int __init idle_setup (char *str)
+{
+	if (!strncmp(str, "poll", 4)) {
+		printk("using polling idle threads.\n");
+		pm_idle = poll_idle;
+	}
+	else{
+	  pm_idle = xen_idle;
+	}
+
+	return 1;
+}
+
+__setup("idle=", idle_setup);
+
 
 /* Prints also some state that isn't saved in the pt_regs */ 
 void __show_regs(struct pt_regs * regs)