Re: [Xen-devel] RTC patch

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 22.08.12 at 17:01, Christoph Egger <Christoph.Egger@xxxxxxx> wrote:
> On 08/22/12 16:47, Jan Beulich wrote:
> 
>>>>> On 22.08.12 at 12:48, Christoph Egger <Christoph.Egger@xxxxxxx> wrote:
>>> On 08/21/12 15:57, Jan Beulich wrote:
>>>
>>>>>>> On 21.08.12 at 15:28, Christoph Egger <Christoph.Egger@xxxxxxx> wrote:
>>>>> On 08/20/12 13:06, Jan Beulich wrote:
>>>>>
>>>>>>>>> On 20.08.12 at 11:17, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
>>>>>>>     * fix high change rate to CMOS RTC periodic interrupt causing
>>>>>>>       guest wall clock time to lag (possible fix outlined, needs to be
>>>>>>>       put in patch form and thoroughly reviewed/tested for unwanted
>>>>>>>       side effects, Jan Beulich)
>>>>>>
>>>>>> Patch was posted, but no comments or approval to commit so far.
>>>>>> Also, reportedly the patch only improves the situation, it doesn't
>>>>>> completely eliminate the problem. For the moment I'm out of ideas,
>>>>>> though, and hence would hope some others could help here.
>>>>>
>>>>>
>>>>> Can you point me to the patch (or resend it to me), please?
>>>>> I have some trouble with getting XP Mode in Windows 7 (nested
>>>>> virtualization) booting and figured out it uses the RTC.
>>>>> I want to give this patch a try.
>>>>
>>>> http://lists.xen.org/archives/html/xen-devel/2012-08/msg01303.html 
>>>
>>> When booting Windows 7 I get a crash due to a NULL pointer dereference
>>> in xen/common/spinlock.c:45.
>>> It looks like the spin lock is not initialized.
>> 
>> I rather think NULL gets passed from pt_update_irq() to
>> rtc_periodic_interrupt(). Yet rtc.c's sole call to
>> create_periodic_time() clearly passes non-NULL. Oh,
>> hpet_set_timer() can pass a literal 8 (which I didn't spot
>> grepping for RTC_IRQ) - could you refine the check in
>> pt_update_irq()
>> 
>>     else if ( irq == RTC_IRQ )
>> 
>> to read
>> 
>>     else if ( irq == RTC_IRQ && pt_priv )
> 
> Yes, Windows 7 boots with this change.

Good, thanks. But I suppose it has no effect on the problem you
wanted to try this for?

Jan


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