Re: [Qemu-devel] [PATCH] re-set rtc date on reset handler

[Blue Swirl]

On Tue, Sep 1, 2009 at 7:22 PM, Glauber Costa<address@hidden> wrote:
> guests without a stable timesource such as kvm-clock will grab the wallclock
> from our rtc chip. However, we only sync the date when we first launch qemu.
> If a guest goes through a series of reboot cycles, it will slowly see time
> getting far behind the host.
>
> The proposal of this patch is to set the date to host clock again in the reset
> handler. With this patch, I see a Fedora guest keeping its clock in sync upon
> an ulimited number of reboots.

A different approach is used in m48t59.c: the guest clock is generated
directly from host clock without any timers and only a fixed offset
(to account for time when guest was stopped) is added, so the clock
will always in sync.