On 29/10/14 13:45, Paolo Bonzini wrote: > > > On 10/29/2014 11:37 AM, Andrew Cooper wrote: >> While testing various nested combinations, XenServer has found that >> modern Windows Server versions must have the hypervisor bit hidden from >> them for them to be happy running HyperV, despite the fact that they >> will make use of the Viridian virtual extensions also provided. > > Right. > >> As a result, while it is certainly advisable for the hypervisor bit to >> be set, CommonHV should be available to be found by paravirtualised >> drivers inside an OS which can't cope with the hypervisor bit set. > > Microsoft should just stop putting arbitrary limitations on their > software; or pay the price which, in this case, is not being able to use > the features from the common specification. I guess what they'd do is > reinvent the RNG as a Viridian extension (if they need it). > > You can certainly do CPUID(0x4F000000) even if HYPERVISOR=0. What you > get back is undefined, but in all likelihood it won't be the > "CommonHVIntf" string. Microsoft already has a specification to obtain a random number via an ACPI device. The VM Generation ID. http://www.microsoft.com/en-us/download/details.aspx?id=30707 David -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
