>> No, it isn't.  ͭ   ͭ >>
>> But MVM-unaware extensions are OK if and only if the whole ruby
>> process don't use MVM features at all.     >> touch MVM things, binary compatibility is broken.  
>> is mandatory for everything.
>>
>
> So, MVM will not be part of 2.0? Cause Matz said breaking even binary compatibility would not be an option...

If ruby code doesn't use MVM APIs, we can't see any incompatibility.
IOW, it is binary api addtion, but it is not binary api change.