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Re: [Qemu-devel] [PATCH 05/10] RTC: Update the RTC clock only when readi
From: |
Juan Quintela |
Subject: |
Re: [Qemu-devel] [PATCH 05/10] RTC: Update the RTC clock only when reading it |
Date: |
Thu, 02 Aug 2012 11:09:09 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.1 (gnu/linux) |
Paolo Bonzini <address@hidden> wrote:
> From: Yang Zhang <address@hidden>
>
> Calculate guest RTC based on the time of the last update, instead of
> using timers. The formula is
>
> (base_rtc + guest_time_now - guest_time_last_update + offset)
>
> Base_rtc is the RTC value when the RTC was last updated.
> Guest_time_now is the guest time when the access happens.
> Guest_time_last_update was the guest time when the RTC was last updated.
> Offset is used when divider reset happens or the set bit is toggled.
>
> The timer is kept in order to signal interrupts, but it only needs to
> run when either UF or AF is cleared. When the bits are both set, the
> timer does not run.
>
> UIP is now synthesized when reading register A. If the timer is not set,
> or if there is more than one second before it (as is the case at the
> end of this series), the leading edge of UIP is computed and the rising
> edge occurs 220us later. If the update timer occurs within one second,
> however, the rising edge of the AF and UF bits should coincide withe
> the falling edge of UIP. We do not know exactly when this will happen
> because there could be delays in the servicing of the timer. Hence, in
> this case reading register A only computes for the rising edge of UIP,
> and latches the bit until the timer is fired and clears it.
>
> Signed-off-by: Yang Zhang <address@hidden>
> Signed-off-by: Paolo Bonzini <address@hidden>
>
> static const VMStateDescription vmstate_rtc = {
> .name = "mc146818rtc",
> - .version_id = 2,
> - .minimum_version_id = 1,
> - .minimum_version_id_old = 1,
> + .version_id = 3,
> + .minimum_version_id = 3,
> + .minimum_version_id_old = 3,
> .post_load = rtc_post_load,
> .fields = (VMStateField []) {
> VMSTATE_BUFFER(cmos_data, RTCState),
> @@ -542,11 +595,12 @@ static const VMStateDescription vmstate_rtc = {
> VMSTATE_INT32(current_tm.tm_year, RTCState),
> VMSTATE_TIMER(periodic_timer, RTCState),
> VMSTATE_INT64(next_periodic_time, RTCState),
> - VMSTATE_INT64(next_second_time, RTCState),
> - VMSTATE_TIMER(second_timer, RTCState),
> - VMSTATE_TIMER(second_timer2, RTCState),
> VMSTATE_UINT32_V(irq_coalesced, RTCState, 2),
> VMSTATE_UINT32_V(period, RTCState, 2),
> + VMSTATE_UINT64_V(base_rtc, RTCState, 3),
> + VMSTATE_UINT64_V(last_update, RTCState, 3),
> + VMSTATE_INT64_V(offset, RTCState, 3),
> + VMSTATE_TIMER_V(update_timer, RTCState, 3),
> VMSTATE_END_OF_LIST()
> }
> };
Why did you remove all the migration from previous versions?
You can't migrate now from version{1,2}, and we used to be able to do
it?
Why did you remove it?
Later, Juan.
- [Qemu-devel] [PATCH 0/10] Remove periodic wakeup from RTC timer, Paolo Bonzini, 2012/08/01
- [Qemu-devel] [PATCH 01/10] RTC: Remove the logic to update time format when DM bit changed, Paolo Bonzini, 2012/08/01
- [Qemu-devel] [PATCH 02/10] RTC: Rename rtc_timer_update, Paolo Bonzini, 2012/08/01
- [Qemu-devel] [PATCH 03/10] RTC: Update interrupt state when interrupts are masked/unmasked, Paolo Bonzini, 2012/08/01
- [Qemu-devel] [PATCH 06/10] vmstate: add VMSTATE_TIMER_V, Paolo Bonzini, 2012/08/01
- [Qemu-devel] [PATCH 06/10] RTC: Add divider reset support, Paolo Bonzini, 2012/08/01
- [Qemu-devel] [PATCH 05/10] RTC: Update the RTC clock only when reading it, Paolo Bonzini, 2012/08/01
- [Qemu-devel] [PATCH 07/10] RTC: Do not fire timer periodically to catch next alarm, Paolo Bonzini, 2012/08/01
- [Qemu-devel] [PATCH 09/10] RTC: Remove the current_tm field, Paolo Bonzini, 2012/08/01
- [Qemu-devel] [PATCH 08/10] RTC: Get and set time without going through s->current_tm, Paolo Bonzini, 2012/08/01
- [Qemu-devel] [PATCH 10/10] RTC: Allow to migrate from old QEMU, Paolo Bonzini, 2012/08/01
- Re: [Qemu-devel] [PATCH 0/10] Remove periodic wakeup from RTC timer, Anthony Liguori, 2012/08/01
- Re: [Qemu-devel] [PATCH 0/10] Remove periodic wakeup from RTC timer, Zhang, Yang Z, 2012/08/01