[vbox-dev] [PATCH] Fix for Guest "OS type" future-compatibility

Frank Mehnert frank.mehnert at oracle.com
Fri Jun 26 13:31:34 GMT 2015


On Friday 26 June 2015 15:13:38 Klaus Espenlaub wrote:
> > As for CPU instructions, I think if the host CPU supports them, it
> > should be enabled/passed on to the guest.
> Talking is cheap. Sorry if that sounds rude, but it's Oracle which would
> have to take the consequences of "make all instructions available to the
> guest", and in this case it would mean months of work, delaying 5.0
> without a visible advantage for the entire user base.

in particular this means that it is NOT sufficient to just enable the
proper CPUID bit to make the guest be aware that the instruction is
supported by the CPU. The VMM has to handle certain edge cases (yes, also
on for non-privileged instructions!) and this is the reason why not every
new instruction can be passed to the guest by default.

Kind regards,

Dr.-Ing. Frank Mehnert | Software Development Director, VirtualBox
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