Re: [Xen-devel] [PATCH 2/2] x86/xen: sync the wallclock when the system time changes

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 28.05.13 at 20:53, John Stultz <john.stultz@xxxxxxxxxx> wrote:
> On 05/28/2013 11:22 AM, David Vrabel wrote:
>>      op.cmd = XENPF_settime;
>> -    op.u.settime.secs = now->tv_sec;
>> -    op.u.settime.nsecs = now->tv_nsec;
>> +    op.u.settime.secs = now.tv_sec;
>> +    op.u.settime.nsecs = now.tv_nsec;
>>      op.u.settime.system_time = xen_clocksource_read();
>>   
>>      ret = HYPERVISOR_dom0_op(&op);
>>      if (ret)
>> -            return ret;
>> +            return 0;
>>   
>> -    /* Set the hardware RTC. */
>> -    return mach_set_rtc_mmss(now);
>> +    last = now;
>> +    next = timespec_add(now, ns_to_timespec(NSEC_PER_SEC / 2));
>>   
> 
> Am I missing the xen_set_wallclock hook here? Your previous patch wanted 
> to call the dom0 op and then set the hardware RTC.

That ought to be intentional: We should update the hypervisor's
software wall clock here, but limit updating of the RTC to whenever
a native kernel would do this (i.e. among other things subject to
CONFIG_RTC_SYSTOHC).

Jan


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