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

[Tim Post <echo@xxxxxxxxxxxx>]

On Mon, 2007-09-17 at 04:16 -0600, Tao Shen wrote:
> 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.

As long as you abide by the GPL v2, yes. You can do whatever you want
with it. If you change it and distribute it, you must also make the
source code with your changes available, as XenSource does.

> 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. 

Its GNU/Linux, I don't think XenSource did much to it save for tweaks
and hooks that allow them to easier manage local resources (i.e. disks).
I'm not sure how much they changed. Go download it, list the packages,
download the source, diff each one and you'll find out :)

> No the Xen Hypervisor 
> "controller and UI" is not GPL, and propriatary.  It just conveniently 
> begins with Xen as a marketing trick.

I don't know about the trick part. Their controls are proprietary. Their
company is named XenSource, they push the development of Xen (GPL), I
don't see why its a problem calling it "XenAnythingTheyWant". They give
us millions of dollars worth of free software, what is there to complain
about? They have a right to profit from their endeavor too. 

Xen is not 'baitware'. Xen (GPL) fits any need that you have, if you are
too lazy to write your own control system, that is not their fault :) If
you want more than the console tools, write your own, or hire a
programmer to write some for you. Then you can sell them too if you
like. Virtual Iron did just that.

> 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.

Xen is free software. XenExpress, XenEnt, XenServer are not free
software. At what point did I call it a beast?
   
> XenEnterprise's non-GPL portion is much smaller compared to the GPL'd 
> portion.

Define smaller? Lines of code or cost of development? :) Both must be
considered. Just looking at the screenshots of XenEnt (and the rest) I
can tell you (off the top of my head) your looking at development costs
in the millions. 

> 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. 

Someone other than me has to explain to you how hypercalls and program
API's work.

> If it's indeed interfaced into the 
> hypervisor, then the windows paravirtualization driver should be open 
> sourced, GPL'd.  

That's up to XenSource. They are under no obligation to make those
drivers free. GPL software is not 'open source', every time you say that
I have to ask you to stop.

Please go read http://gnu.org http://fsf.org for more clarification on
the definition of free software and the terms of the GNU GPL license. 

Best,
--Tim


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