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Re: [Xen-users] RE: Does it legal to analysize XEN source code and write a book about it

  • To: Simon Crosby <simon@xxxxxxxxxxxxx>
  • From: Tao Shen <taoshen1983@xxxxxxxxx>
  • Date: Mon, 17 Sep 2007 05:11:25 -0600
  • Cc: xen-users@xxxxxxxxxxxxxxxxxxx
  • Delivery-date: Mon, 17 Sep 2007 04:12:27 -0700
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  • List-id: Xen user discussion <xen-users.lists.xensource.com>

Thanks for your input. I am amazed that most people view my inputs as if I don't know what I am talking about.

Let us just be blunt with each other with facts, you may correct me if I am wrong:

1. Xen the hypervisor is free, and GPL'd, you may copy, distribute, do whatever with it. 2. XenExpress, Xen Server(windows), Xen Enterprise is just a crust, a Xen Hypervisor controller and an UI, similar to open source and free Virt-manager from redhat or the web based enomalism, running on a special Xen created Linux distribution. No the Xen Hypervisor "controller and UI" is not GPL, and propriatary. It just conveniently begins with Xen as a marketing trick. 3. In other words, you have a non-GPL'd controller application wrapped around an opensourced Xen hypervisor running on a GPL'd but custom Linux distribution made by XenSource. It's crazy how many people on this list say "oh Xen is GPL, but XenEnterprise is not" As Tim Post almost made an impression that XenEnterprise is a complete beast compared to Xen. XenEnterprise's non-GPL portion is much smaller compared to the GPL'd portion. 4. The issues with closed source Windows Paravirtualization is this: whether or not it's merged to the Xen Server/Enterprise source tree(the controller and UI parts, which is not GPL'd) or it's interfaced to the Xen hypervisor source tree(which is GPL'd). From a practical point of view, I don't see how a paravirtualized driver can be non-dependent on the GPL'd Xen Hypervisor. If it's indeed interfaced into the hypervisor, then the windows paravirtualization driver should be open sourced, GPL'd. I don't know the exact software dependence choice made by XenSource, and you may provide more information.

Few more points to add:
5. I do know, and have read the GPL. Notice that I said "pushing the boundary of the GPL?", not "against GPL". The reason being is that Xen Enterprise is a GPL'd custom Linux OS wrapping around an non-GPL'd controller GUI application wrapping around an GPL'd Xen Hypervisor interfaced to a nonGPL'd Paravirtualized Windows Hypervisor Driver, and then marketed as if the whole thing is non-GPL'd. That's the issue I have.

6. I understand that Citrix bought XenSource the company, not Xen. And it's a perfectly legal thing to do. However, if you want to be brutally honest, did Citrix really just buy XenEnterprise the crust? of course not, as the free Xen is as core to the company as you can imagine. So yes, Citrix did buy Xen the hypervisor and kept it GPL'd. Citrix also bought a group of highly talented people versed in Xen code, which is the primary reason why they did it. So I really really don't want to hear people say, Oh Citrix didn't buy Xen the hypervisor. It's really BS. If they bought the crust, they bought the core, it's as simple as that. The real question is then, it is ethical to wrap a thin layer around a core GPL'd product and sell it whole. No, it's not technically against GPL...it's pushing it. That's the point I wanted to make and that's what I said, and people have been all over me for it as if I don't understand the open source ecosystem.

7. Some of the examples in the open source industry right now include: using PostgreSQL based code which is GPL'd, add a non-GPL'd replication suite to it, and call it enterpriseDB. Using PostgreSQL based code, tweak some variables, add some non-GPL'd code (interfaced to the GPL'd one) to do distributed join and call it "bizgres" and "greenplum". MySQL's Enterprise vs Community editions....the examples are all other the place. All of them push the GPL boundary but don't violate it. And what I call the "wrapper GPL" type products, and "dual licensing". No, it's all perfect legal. From an ethics perspective...it's arguable.

Feel free to discuss this as you see fit.


Simon Crosby wrote:
Please see my response to two messages below:

Message: 3
Date: Fri, 14 Sep 2007 09:56:54 +0800
From: "jian zhang" <cheechuang@xxxxxxxxx>
Subject: [Xen-users] Does it legal to analysize XEN source code and
    write a    book about it ?
To: xen-users <xen-users@xxxxxxxxxxxxxxxxxxx>
Content-Type: text/plain; charset="iso-8859-1"

Hi all:
Previously we have analysize Xen source code, and we have wrote a book about the code. BUT now, I noticed that xen has been purchased by Citrix<http://www.cnetnews.com.cn/list-0-0-16406-0-1.htm>,
so does it legal to publish that book???

Of course!  Xen is GPL, and there are several books about it already.
Indeed you can freely use the name Xen to describe it, but you should
acknowledge the trademark, which is owned by XenSource but held in trust
for the community and licensed without royalty to any vendors that
implement Xen.

More books are needed to help grow the community and continue to bring
the benefits of Xen to a wider audience.  Thanks for your work.

Message: 4
Date: Thu, 13 Sep 2007 21:09:58 -0600
From: Tao Shen <taoshen1983@xxxxxxxxx>
Subject: Re: [Xen-users] Does it legal to analysize XEN source code
    and write    a    book about it ?
To: jian zhang <cheechuang@xxxxxxxxx>

Well, my point is this: if you have "analysize"d Xen, perhaps you shouldn't have written a book about it, at least not in English.

That's not particularly nice.  Particularly given that your own analysis
is so flawed.

On the issue of Xen being purchased by Citrix, I was wondering about the issues of legality. Is it even legal for a corporation(Citrix) to purchase an open source package, of which was contributed by thousands of open source developers, and is it legal for a corporation(XenSource) who basically combines a lot of open source package(qemu device drivers and their paravirtualization based on the linux kernel) into one to sell the technology as if they owned it?

Citrix has announced that it intends to purchase XenSource, not Xen.
Xen is GPL software, community authored and owned, and always will be.
Citrix has announced that it will strengthen and enhance the community
and dedicate significantly more resource to the community than XenSource
could afford to.

When Xen was doing their Xen Enterprise, Xen Windows, and Xen Express separation, I knew this XenSource was going to be bought. While it's perfectly legal for XenSource to provide open source service...selling support packages(to amazon EC2 for example), but forcing the bundling of support with an "enterprise" edition is pushing the boundaries of GPL.

I suggest you read the GPL.  XenSource ensures that at all times the
very best version of the Xen hypervisor is available to the entire
community.  The power of Xen is that there are multiple routes to market
for the core "engine": our own products, Linux distros, Sun etc etc. We respect the GPL to the letter. Our product combines GPL Xen with
XenSource add-on software that enables us to serve the broad market need
for Virtualization, which is dominated by the Windows OS.  Some of what
we do is closed source - sometimes by legal requirement.  You will find
that Novell has the same approach for their (proprietary) Windows PV
drivers.  Moreover Novell will use Xen with proprietary tools and a
proprietary OS (NetWare) in OES.  All of this is entirely legal, since
the boundaries between GPL and non GPL code in the Xen code base are
explicit and very deliberate.

At least that's my understanding of the GPL.

Might I suggest that you re-read it?

Comparing this behavior to VMware or Parallels, at least VMware and Parallels wrote their code they are selling. Every line of it.

There are many who differ from your view:

The remainder of your post unfortunately contains so many inaccuracies
that it is quite honestly not worthwhile rebutting them line for line.

XenSource is wholly committed to open source as the most powerful
vehicle of innovation, and to the community as the most powerful vehicle
of delivery of powerful feature sets and powerful products.  We endorse
multiple vendors delivering the Xen hypervisor to market, in their own
differentiated products.

Simon Crosby, CTO

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