Re: [Xen-devel] vsyscall support in 2.6.{32,33}

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

 On 09/21/2010 06:09 AM, Pasi Kärkkäinen wrote:
> On Tue, Sep 21, 2010 at 02:49:17PM +0200, Paolo Bonzini wrote:
>> Besides the obvious fact that the required hypercall is not supported by  
>> any released hypervisor, is there any other reason why the xen vsyscall  
>> code is not in the pvops/stable-2.6.{32,33}.x branches?
>>
>> Thanks!
>>
> I guess Jeremy didn't remember to merge it yet? :)
> Or is there some problem with it?
>

The main problem is that I'm not sure that the Xen clock algorithm can
give strict enough monotonicity for usermode use (ie, can't meet the
expected behaviour of clock_gettime()), and its not at all clear how to
fix it.  I could prevent non-monotonicity within one process, but not
between processes.

    J

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