[v3,4/4] vl, qapi: offset calculation in RTC_CHANGE event reverted

Commit Message

Artem Pisarenko Oct. 18, 2018, 7:12 a.m. UTC

Return value of qemu_timedate_diff(), used for calculation offset in
QAPI 'RTC_CHANGE' event, restored to keep compatibility. Since it
wasn't documented that difference is relative to host clock
advancement, this change also adds important note to 'RTC_CHANGE'
event description to highlight established implementation specifics.

Signed-off-by: Artem Pisarenko <[e-mail]>
---
 qapi/misc.json |  3 ++-
 vl.c           | 10 +++++-----
 2 files changed, 7 insertions(+), 6 deletions(-)

Patch

diff --git a/qapi/misc.json b/qapi/misc.json
index ada9af5..d0f5381 100644
--- a/qapi/misc.json
+++ b/qapi/misc.json
@@ -3070,7 +3070,8 @@ 
 # Emitted when the guest changes the RTC time.
 #
 # @offset: offset between base RTC clock (as specified by -rtc base), and
-#          new RTC clock value
+#          new RTC clock value. Note that value will be different depending
+#          on clock chosen to drive RTC (specified by -rtc clock).
 #
 # Note: This event is rate-limited.
 #
diff --git a/vl.c b/vl.c
index 78a8a68..c350aba 100644
--- a/vl.c
+++ b/vl.c
@@ -788,10 +788,10 @@  void qemu_system_vmstop_request(RunState state)
 
 /***********************************************************/
 /* RTC reference time/date access */
-static time_t qemu_ref_timedate(void)
+static time_t qemu_ref_timedate(QEMUClockType clock)
 {
-    time_t value = qemu_clock_get_ms(rtc_clock) / 1000;
-    switch (rtc_clock) {
+    time_t value = qemu_clock_get_ms(clock) / 1000;
+    switch (clock) {
     case QEMU_CLOCK_REALTIME:
         value -= rtc_realtime_clock_offset;
         /* no break */
@@ -811,7 +811,7 @@  static time_t qemu_ref_timedate(void)
 
 void qemu_get_timedate(struct tm *tm, int offset)
 {
-    time_t ti = qemu_ref_timedate();
+    time_t ti = qemu_ref_timedate(rtc_clock);
 
     ti += offset;
 
@@ -849,7 +849,7 @@  int qemu_timedate_diff(struct tm *tm)
         break;
     }
 
-    return seconds - qemu_ref_timedate();
+    return seconds - qemu_ref_timedate(QEMU_CLOCK_HOST);
 }
 
 static void configure_rtc_base_datetime(const char *startdate)