path: root/Documentation/rtc.txt
diff options
authorJean Delvare <khali@linux-fr.org>2006-06-25 12:48:23 (GMT)
committerLinus Torvalds <torvalds@g5.osdl.org>2006-06-25 17:01:14 (GMT)
commit9be05b57bd9152b7c26b1599b87aeb42a102f0cf (patch)
treec09b9505af968ffaab852c7e09db7b5262f863b9 /Documentation/rtc.txt
parent8e12ecc2b5a4521a338d7681e7d5547080fc6f71 (diff)
[PATCH] rtc: small documentation update
Rtc driver documentation update * Mention the max-user-freq control file. * Add missing header in example code. Signed-off-by: Jean Delvare <khali@linux-fr.org> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'Documentation/rtc.txt')
1 files changed, 5 insertions, 2 deletions
diff --git a/Documentation/rtc.txt b/Documentation/rtc.txt
index 95d17b3..2a58f98 100644
--- a/Documentation/rtc.txt
+++ b/Documentation/rtc.txt
@@ -44,8 +44,10 @@ normal timer interrupt, which is 100Hz.
Programming and/or enabling interrupt frequencies greater than 64Hz is
only allowed by root. This is perhaps a bit conservative, but we don't want
an evil user generating lots of IRQs on a slow 386sx-16, where it might have
-a negative impact on performance. Note that the interrupt handler is only
-a few lines of code to minimize any possibility of this effect.
+a negative impact on performance. This 64Hz limit can be changed by writing
+a different value to /proc/sys/dev/rtc/max-user-freq. Note that the
+interrupt handler is only a few lines of code to minimize any possibility
+of this effect.
Also, if the kernel time is synchronized with an external source, the
kernel will write the time back to the CMOS clock every 11 minutes. In
@@ -81,6 +83,7 @@ that will be using this driver.
#include <stdio.h>
+#include <stdlib.h>
#include <linux/rtc.h>
#include <sys/ioctl.h>
#include <sys/time.h>