Re: 2.6.32.2: undefined reference to `__udivdi3'

[Stephen Hemminger]

The new menu governor driver is written by Intel folks who never use 32-bit
anymore it seems :-)
---------------------------------------------------------
Subject: [PATCH] menu: use proper 64 bit math

The new menu governor is incorrectly doing a 64 bit divide.
Compile tested only

Signed-off-by: Stephen Hemminger <shemminger@xxxxxxxxxx>

--- a/drivers/cpuidle/governors/menu.c	2009-12-21 12:02:25.840083589 -0800
+++ b/drivers/cpuidle/governors/menu.c	2009-12-21 12:16:42.418834255 -0800
@@ -18,6 +18,7 @@
 #include <linux/hrtimer.h>
 #include <linux/tick.h>
 #include <linux/sched.h>
+#include <linux/math64.h>
 
 #define BUCKETS 12
 #define RESOLUTION 1024
@@ -169,6 +170,12 @@ static DEFINE_PER_CPU(struct menu_device
 
 static void menu_update(struct cpuidle_device *dev);
 
+/* This implements DIV_ROUND_CLOSEST but avoids 64 bit division */
+static u64 div_round64(u64 dividend, u32 divisor)
+{
+	return div_u64(dividend + (divisor / 2), divisor);
+}
+
 /**
  * menu_select - selects the next idle state to enter
  * @dev: the CPU
@@ -209,9 +216,8 @@ static int menu_select(struct cpuidle_de
 		data->correction_factor[data->bucket] = RESOLUTION * DECAY;
 
 	/* Make sure to round up for half microseconds */
-	data->predicted_us = DIV_ROUND_CLOSEST(
-		data->expected_us * data->correction_factor[data->bucket],
-		RESOLUTION * DECAY);
+	data->predicted_us = div_round64(data->expected_us * data->correction_factor[data->bucket],
+					 RESOLUTION * DECAY);
 
 	/*
 	 * We want to default to C1 (hlt), not to busy polling
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/