Ok, thanks! this is enought to get started.
but how can I read a random number from /dev/urandom? is Xend the deamon
that you talk me about?

Thanks
Michele


On Fri, Feb 12, 2010 at 1:15 PM, George Dunlap
<George.Dunlap@eu.citrix.com>wrote:

> I think the short answer is, Xen does not have a mechanism to collect
> true randomness at the moment.  I'm not an expert in random numbers,
> so the bitrate doesn't mean anything to me.  A couple of possible
> solutions come to mind:
> * Use pseudo-random numbers to start out with and test your theories,
> while working on getting truly random numbers in.
> * Punt the problem to dom0: Have a daemon in dom0 to read /dev/urandom
> and "upload" values into a ring read by Xen.  If the ring is empty,
> use pseudo-random numbers seeded by old values in the ring (?).
> * Add entropy-collection to Xen.
> * If interrupted by a timer that's longer than 1ms, just take a TSC
> and lop off the lower 10 bits.  If you haven't been interrupted by a
> timer, use pseudorandom numbers seeded by the lower 10 bits of the
> last TSC.
>
> As I said, I'm not an expert in collecting entropy, so some of these
> may be obviously brain-dead ideas.  But it might give you enough to
> get started.
>
>  -George
>
> On Fri, Feb 12, 2010 at 8:32 AM, michele.paolino
> <michele.paolino@studio.unibo.it> wrote:
> > I need less than 10 bits at rate of 10 milliseconds. With a random number
> I
> > will select the next VCPU to schedule.
> >
> > Michele
> >
> > On Fri, Feb 12, 2010 at 2:51 AM, James Harper
> > <james.harper@bendigoit.com.au> wrote:
> >>
> >> >
> >> > Hi!
> >> > I am interested in writing a scheduler for Xen for academic purposes.
> >> I need
> >> > to generate random numbers.
> >> > Is it possible to generate random numbers in xen hypervisor
> >> developement?If
> >> > this is possible, how can I do it?
> >> >
> >>
> >> How many bits do you random numbers need to be?
> >>
> >> At what rate do you need them? (10/second?, 1000000/second?)
> >>
> >> Would pseudo-random numbers do? If so, what repeat interval is
> >> sufficient?
> >>
> >> James
> >
> >
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> > http://lists.xensource.com/xen-devel
> >
> >
>