Re: [Qemu-devel] [PATCH 0/5] mc146818rtc: fix Windows VM clock faster

[Xiao Guangrong]

On 04/14/2017 01:09 PM, Paolo Bonzini wrote:
> On 13/04/2017 16:52, Xiao Guangrong wrote:
> > On 04/13/2017 04:39 PM, Xiao Guangrong wrote:
> > > On 04/13/2017 02:37 PM, Paolo Bonzini wrote:
> > > > However, I think that the above should be exactly how the RTC should
> > > > work.  The original RTC circuit had 22 divider stages (see page 13 of
> > > > the datasheet[1], at the bottom right), and the periodic interrupt taps
> > > > the rising edge of one of the dividers (page 16, second paragraph).  The
> > > > datasheet also never mentions a comparator being used to trigger the
> > > > periodic interrupts.
> > >
> > > That was my thought before, however, after more test, i am not sure if
> > > re-configuring RegA changes these divider stages internal...
>
> It's unlikely because there is a separate divider reset command.  But
> Hailiang found the same problem, and Bochs does the same implementation
> as you.

Happy to see the same approach is being used in Bochs. Thanks for your
check. :)