[Qemu-devel] [PATCH v3 0/7] RTC: New logic to emulate RTC

[Zhang, Yang Z]

Changes in v3:
Rebase to latest head.
Remove the logic to update time format when DM bit changed.
Allow to migrate from old version.
Solve the async when reading UF and UIP

Changes in v2:
Add UIP check logic.
Add logic that next second tick will occur in exactly 500ms later after reset 
divider

Current RTC emulation uses periodic timer(2 timers per second) to update RTC 
clock. And it will stop CPU staying at deep C-state for long period. Our 
experience shows the Pkg C6 residency reduced 6% when running 64 idle guest.
The following patch stop the two periodic timer and only updating RTC clock 
when guest try to read it.
--- 
Yang Zhang (7):
        RTC: Remove the logic to update time format when DM bit changed
        RTC: Update the RTC clock only when reading it
        RTC: Add UIP(update in progress) check logic
        RTC: Set internal millisecond register to 500ms when reset divider
        RTC: Add RTC update-ended interrupt support
        RTC: Add alarm support
        RTC: Allow to migrate from old version

        hw/mc146818rtc.c |  427 
++++++++++++++++++++++++++++++++++-------------------
        1 files changed, 274 insertions(+), 153 deletions(-)

best regards
yang