Re: [Qemu-devel] [RFC] RFC on Backup tool

[Eric Blake]

On 07/18/2017 04:29 PM, John Snow wrote:
>>>
>>> You need a copyright header here (the default choice for QEMU is GPLv2 but 
>>> there
>>> is no strict restrictions for scripts). See examples in other *.py files.
>>
>> Thanks. Will update in next revision.
>>  
> 
> Yes, up to you. Files without a copyright default to GPLv2 in the QEMU
> project, but if you feel strongly one way or another you can argue for
> that license in upstream review.

More precisely, the qemu binary is GPLv2 (only), as that is the only
license compatible as the sum of its parts.  But new files default to
GPLv2+ (upgradable to GPLv3, except when mixed with GPLv2-only code).

> 
> (For instance, documentation and other non-code documents can sometimes
> be better served by different licenses.)

Indeed, some people (not me) express concern whether a specification
documentation that is GPL would require all implementations of that
specification to also be GPL, and thus intentionally choose a more
permissive license for the documentation (BSD being a common example).
(Personally, I think that a GPL specification merely means that you
can't copy the docs without your copy being GPL, but that you can still
implement the specification using from-scratch non-GPL code - but I'm
not a lawyer, so listening to me may not be the best thing)

> 
> We tend to avoid the implicit copyright when possible, so including an
> explicit GPLv2 license is preferable to declare intent.

Remember, an explicit GPLv2-only license needs strong justification,
since the implicit license is GPLv2+.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

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