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[Xen-devel] Re: Is Continuous replication of state possible?


  • To: xen-devel@xxxxxxxxxxxxxxxxxxxxx
  • From: George Washington Dunlap III <dunlapg@xxxxxxxxx>
  • Date: Fri, 7 Jan 2005 12:51:45 -0500 (EST)
  • Delivery-date: Fri, 07 Jan 2005 19:19:38 +0000
  • List-id: List for Xen developers <xen-devel.lists.sourceforge.net>

On Fri, 7 Jan 2005 xen-devel-request@xxxxxxxxxxxxxxxxxxxxx wrote:

This will be hard when running crypto programs that get
their random numbers directly from the CPU ...

Yes, any sort of non-deterministic instruction must be either made to execute the same, or disallowed. :-)

I'm not familiar with the setup of those kinds of CPUs. Is this situation any different than that of RDTSC? We can't allow native execution of RDTSC on different platforms either.

More annoying is the CPUID instruction, which is non-privileged (and so cannot be trapped & emulated like RDTSC), but returns different results on processors that are not identical...

 -George Dunlap

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