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RE: [Xen-devel] Windows DDK and GPL

To: "Steve Ofsthun" <sofsthun@xxxxxxxxxxxxxxx>, "James Harper" <james.harper@xxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] Windows DDK and GPL
From: "Vessey, Bruce A" <Bruce.Vessey@xxxxxxxxxx>
Date: Fri, 21 Sep 2007 13:57:25 -0500
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Thread-topic: [Xen-devel] Windows DDK and GPL
I attempted to reply to James and this mail list this morning, but now
notice that I inadvertantly responded only to James.  Here's what I

In the past I had speculated that this might be the case.  It's been a
few years since I've had to worry about the DDK license, so it would be
great if somebody with up-to-date information could comment.  However,
there's an interesting posting about the WDK EULA restrictions at
http://www.osronline.com/ShowThread.cfm?link=101027  (BTW, with it's
release for Vista, the "DDK" is now called a "WDK".)

Bottom line: You (and/or your lawyers) need to get a copy of the WDK
EULA and review it in light of whatever you're trying to do. 

    - Bruce  

-----Original Message-----
From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Steve
Sent: Friday, September 21, 2007 2:53 PM
To: James Harper
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-devel] Windows DDK and GPL

James Harper wrote:
> During a recent discussion about the PV drivers for windows, someone 
> made a comment about (I'm paraphrasing from memory here, I might be 
> completely wrong) the Windows DDK being incompatible with the GPL, and

> thus even if you wanted to, any driver developed under the DDK could 
> not be released under the GPL, or maybe even any other OSS license...
> Can anyone point me to something which explicitly clarifies this? Or 
> correct me if my interpretation is incorrect?

Here is a note from Bruce Vessey at Unisys from 11/01/2006.  Not so
recent, but the link to the EULA still works.

> It would be nice if somebody releases HVM paravirt drivers for Windows

> as open source, but I'm not holding my breath.  Why?  Because of the 
> Microsoft DDK license.  There's no requirement that a Windows device 
> driver developer use the Microsoft DDK, but in my experience most do.
> The typical methodology for a Windows driver developer is to take the 
> sample code from the DDK as a starting point, and build the driver 
> from there.  But the DDK has some interesting licensing restrictions 
> that, to me, don't look compatible with open source.  The Microsoft 
> DDK license is available at 
> http://www.microsoft.com/whdc/devtools/ddk/ServerSP1DDKEULA.mspx
> Sections 3 & 4 look particularly problematic.
> Maybe somebody out there is developing (or has developed) Windows 
> drivers without any encumbrances from the Windows DDK.  I think that's

> the only way we'll see open source Windows drivers.

Our Windows driver set is built using the Microsoft DDK.

Aside from any legal issues, our implementation of HVM live migrate is
not binary compatible with the current Xen 3.1 release.  This and other
compatibility issues (our 32 bit drivers use the same ring protocol as
64 bit drivers) would prevent you from using our drivers directly.  This
is not a planned divergence, rather a consequence of getting something
to work reliably enough to ship at various points since 3.0.2.  Over
time we have been converging with generic XEN and at some future date I
would expect binary compatibility.

If a source distribution was not available, would a binary release be of
any use?

Hope this helps,
Steve Ofsthun - Virtual Iron Software, Inc.

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