[libvirt] libvirt Hyper-v 2012 r2 fix

[Eric Blake]

On 04/16/2014 05:51 PM, vikhyath reddy wrote:

> With these changes and a few other minor ones, I can confirm that the
> functionality mimics the hyperv 2008 version. That is, we get the same
> functionality (supported vs non-supported drivers).
> 
> However, this might also mean the end of support of Hyper-V 2008 if it is
> just a replace of the existing classes. What do you guys think? Should we
> continue to support 2008 (~6 years old) OR is it OK to assume that Hyperv-V
> 2012 will be the default standard moving forward.

At least for qemu and xen, we try hard to support any version of a
hypervisor that is still actively supported by at least one vendor (that
is, RHEL 5 is our current limit of how far back we try and support).  On
the other hand, free software is somewhat easier to support than
proprietary software (we have access to the source code, and can make
decisions about how to work around old constructs or even see how newer
versions changed in relation to older versions - a luxury not available
when targetting something where only the interface is public but the
source code is hidden).

I'm not sure how far back Microsoft supports old versions of Hyper-V,
especially given the recent media attention to the fact that they
explicitly no longer support Windows XP.  Although Hyper-V 2008 is 6
years old, if it is still actively supported (where I could buy a
license today and still get support for the product), then libvirt
should still consider targetting it.  On the other hand, patches speak
louder than words - anyone interested enough to actually post a patch,
even if it actively excludes an older version of the hypervisor, has
more clout than someone like me that has never even used Hyper-V :)  So
I guess that means it is your call on whether it is easier to drop
support for old versions for the sake of making maintenance easier.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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