Re: [Xen-devel] [licensing] was: [XTF PATCH 04/16] vvmx: add C wrappers of vmxon/vmread/vmptrld

[Haozhong Zhang <haozhong.zhang@xxxxxxxxx>]

On 12/16/16 19:03 +0000, Andrew Cooper wrote:
> On 16/12/16 13:43, Haozhong Zhang wrote:
> > diff --git a/include/arch/x86/hvm/vmx/vmcs.h b/include/arch/x86/hvm/vmx/vmcs.h
> > new file mode 100644
> > index 0000000..e1a6ef8
> > --- /dev/null
> > +++ b/include/arch/x86/hvm/vmx/vmcs.h
> > @@ -0,0 +1,179 @@
> > +#ifndef XTF_X86_HVM_VMX_VMCS_H
> > +#define XTF_X86_HVM_VMX_VMCS_H
> > +
> > +/* VMCS field encodings. */
> > +#define VMCS_HIGH(x) ((x) | 1)
> > +enum vmcs_field {
> > +    VIRTUAL_PROCESSOR_ID            = 0x00000000,
> > +    POSTED_INTR_NOTIFICATION_VECTOR = 0x00000002,
> > +    EPTP_INDEX                      = 0x00000004,
> > +#define GUEST_SEG_SELECTOR(sel) (GUEST_ES_SELECTOR + (sel) * 2) /* ES ... GS */
> Unfortunately, there is probably a BSD/GPL licensing issue here.
>
> XTF is BSD clause 2 licensed, because a lot of the core microkernel bits
> are generally useful to other microkernel projects, and I have specific
> plans to contribute improvements back to the likes of Mini-OS and
> HVMLoader.  I would specifically like to maintain this property.
>
> Xen, following its Linux heritage, is strictly GPLv2 (other than the
> public headers, which are specifically different).
>
>
> Having XTF use the same naming as Xen is convenient for development, and
> I specifically don't want to get caught up in tricks like renaming
> constants;
but renaming or taking names from other BSD-licensed projects [1] could
keep the whole project as purely BSD-licensed.

[1] https://github.com/freebsd/freebsd/blob/master/sys/amd64/vmm/intel/vmcs.h

> these names inherit from the architecture manual and calling
> them anything else would be even worse. If we were to go down this
> route, being able to keep the header file in sync would be useful, but
> dual licensing it Xen would be complicated and confusing.
>
> BSD and GPL are compatible licenses.  One option Ian suggested would be
> to have a GPL subdirectory in XTF which clearly separates GPL content
> from BSD content.  The resulting tests would become GPL, but the primary
> distribution method is "git clone && make", so there are no issues
> there.
If I want to use the BSD-licensed files individually in other
projects, will I need to keep a GPL license with them?

Thanks,
Haozhong

> I think it is reasonable to take this approach for header file
> content like this, describing an external ABI, but I'd certainly like to
> avoid doing anything similar for other content, as it complicates
> contributing microkernel content back to other projects.
>
> CC'ing various people for opinions.
>
> ~Andrew
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