Re: [Qemu-devel] [PATCH 7/7] RTC: Allow to migrate from old QEMU

[Paolo Bonzini <pbonzini@redhat.com>]

Il 23/07/2012 07:12, Juan Quintela ha scritto:
>     .fields      = (VMStateField []) {
>         VMSTATE_BUFFER(cmos_data, RTCState),
>         VMSTATE_UINT8(cmos_index, RTCState),
>         VMSTATE_INT32(current_tm.tm_sec, RTCState),
>         VMSTATE_INT32(current_tm.tm_min, RTCState),
>         VMSTATE_INT32(current_tm.tm_hour, RTCState),
>         VMSTATE_INT32(current_tm.tm_wday, RTCState),
>         VMSTATE_INT32(current_tm.tm_mday, RTCState),
>         VMSTATE_INT32(current_tm.tm_mon, RTCState),
>         VMSTATE_INT32(current_tm.tm_year, RTCState),
> 
> you can change this to:
> 
>         VMSTATE_UNUSED(7*4);

I think this is not safe.  In the load_old case, we ignore the struct tm
because we call rtc_set_time and check_update_timer.  We need this to
make up some values of base_rtc, last_update and offset.

In the normal case we need both the CMOS data and the timer data.
Though perhaps I can make a further change and remove current_tm
altogether.  I'll take a look this week; however that will make it even
harder to produce the old version.

Paolo