Re: [Xen-devel] Re: [PATCH] [PVOPS] dom0 sync xen wallclock

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 19/02/2010 09:10, "Ian Campbell" <Ian.Campbell@xxxxxxxxxx> wrote:

> On Thu, 2010-02-18 at 23:43 +0000, Jeremy Fitzhardinge wrote:
>>     * PV domUs get a rough time of day at boot either from a simple
>>       "seconds since 1970" in the startup info put there by the domain
>>       builder from dom0's clock (so there's no illusion that it is
>>       anything other than a one-time start time for the domain)
> 
> Unfortunately there is an existing large installed base of guests which
> use the dependent wallclock mode since it is the default in oldstyle Xen
> kernels.

That still plays okay with dom0 setting Xen wallclock only once, or not at
all (since Xen primes its WC values from CMOS). The wallclock values would
then never change and old kernels naturally just pick up WC at boot and
never again. And their default mode is also compatible with them running
ntpd -- if the kernel detects ntp sync then it changes/reduces how it syncs
with Xen.

 -- Keir



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel