[Qemu-devel] [PATCH] Do not set RTC frequency if already set

[Aurelien Jarno <aurelien@aurel32.net>]

Do not set RTC frequency to 1024 or warn about this if it has already
been set to the correct value.

---
 vl.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/vl.c b/vl.c
index 8c63ad9..2d494c5 100644
--- a/vl.c
+++ b/vl.c
@@ -1307,11 +1307,14 @@ static void hpet_stop_timer(struct qemu_alarm_timer *t)
 static int rtc_start_timer(struct qemu_alarm_timer *t)
 {
     int rtc_fd;
+    unsigned long current_rtc_freq = 0;
 
     TFR(rtc_fd = open("/dev/rtc", O_RDONLY));
     if (rtc_fd < 0)
         return -1;
-    if (ioctl(rtc_fd, RTC_IRQP_SET, RTC_FREQ) < 0) {
+    ioctl(rtc_fd, RTC_IRQP_READ, &current_rtc_freq);
+    if (current_rtc_freq != RTC_FREQ &&
+        ioctl(rtc_fd, RTC_IRQP_SET, RTC_FREQ) < 0) {
         fprintf(stderr, "Could not configure '/dev/rtc' to have a 1024 Hz timer. This is not a fatal\n"
                 "error, but for better emulation accuracy either use a 2.6 host Linux kernel or\n"
                 "type 'echo 1024 > /proc/sys/dev/rtc/max-user-freq' as root.\n");

-- 
  .''`.  Aurelien Jarno	            | GPG: 1024D/F1BCDB73
 : :' :  Debian developer           | Electrical Engineer
 `. `'   aurel32@debian.org         | aurelien@aurel32.net
   `-    people.debian.org/~aurel32 | www.aurel32.net