Cygwin [LWN.net]

Cygwin

Posted Nov 19, 2008 22:40 UTC (Wed) by rwmj (subscriber, #5474)
In reply to: Cygwin by jengelh
Parent article: MinGW and why Linux users should care

cygwin1.dll is GPL'd, so incompatible with LGPL libraries.

And it does a whole layer of Unix emulation, whereas this is a direct port to the Win32 API.

to post comments

LGPL is compatible with Cygwin's license (GPL+exceptions)

Posted Nov 20, 2008 2:50 UTC (Thu) by dwheeler (guest, #1216) [Link] (6 responses)

First of all, the LGPL is typically compatible with the GPL, depending on their versions. See my FLOSS License Slide for more information on license compatibility.

BUT Cygwin's license is special: you can use ANY open source software license, without charge, with Cygwin. You can also use Cygwin to run closed source software, but you have to pay extra for that privilege. The Cygwin license, which is the GPL plus some exceptions, is at: http://www.cygwin.com/licensing.html.

The Cygwin license says: "Red Hat permits programs whose sources are distributed under a license that complies with the Open Source Definition [See http://www.opensource.org/docs/osd/ for the precise Open Source Definition and a list of the licenses certified by OSI as conforming to that definition] to be linked with libcygwin.a/cygwin1.dll without libcygwin.a/cygwin1.dll itself causing the resulting program to be covered by the GNU GPL. This means that you can port an Open Source application to Cygwin (TM), and distribute that executable as if it didn't include a copy of libcygwin.a/cygwin1.dll linked into it... Red Hat sells a special Cygwin (TM) License for customers who are unable to provide their application in open source code form."

LGPL is NOT compatible with Cygwin's license (GPL+exceptions)

Posted Nov 20, 2008 8:07 UTC (Thu) by rwmj (subscriber, #5474) [Link] (3 responses)

The people who are using libvirt are mostly developing a mix of in-house and proprietary
applications. They don't want to open source their code, nor do we want to discriminate against
them by making them by a special license. They don't need to buy a special license for libvirt on
Linux, nor to use proprietary APIs such as VMWare API / XenAPI.

LGPL is NOT compatible with Cygwin's license (GPL+exceptions)

Posted Nov 20, 2008 12:21 UTC (Thu) by fuhchee (guest, #40059) [Link] (2 responses)

nor do we want to discriminate against them by making them buy a special license

Since you consider licensing-based incentives to create free software as discrimination, what prevented you from (say) releasing libvirt into the public domain?

LGPL is NOT compatible with Cygwin's license (GPL+exceptions)

Posted Nov 20, 2008 12:35 UTC (Thu) by rwmj (subscriber, #5474) [Link]

LGPL protects the libvirt code while not imposing itself on other code that we didn't write.

As a free software developer yourself, you should know the difference between public domain, LGPL
and GPL.

LGPL is NOT compatible with Cygwin's license (GPL+exceptions)

Posted Nov 20, 2008 12:36 UTC (Thu) by nix (subscriber, #2304) [Link]

This is a *management layer*. It's going to get used by people who have existing virtualization systems and want to manage them. Nobody, but nobody is going to say 'hey! my management layer uses GPL, so I should switch virtualization systems to one that is GPL!'. They'll just not use libvirt.

This is a classic example of a library that is better LGPLed than GPLed.

LGPL is compatible with Cygwin's license (GPL+exceptions)

Posted Nov 21, 2008 17:39 UTC (Fri) by giraffedata (guest, #1954) [Link] (1 responses)

Red Hat permits [open source programs] to be linked with libcygwin.a/cygwin1.dll without libcygwin.a/cygwin1.dll itself causing the resulting program to be covered by the GNU GPL.

This wording shows a typical misunderstanding of copyright, wherein someone thinks a copyright license is something that restricts you in distributing software.

If the resulting program is not covered by GPL, nobody has Red Hat's permission to distribute it at all. (We assume of course that it's a derivative work so that Red Hat has copyright, because otherwise nobody needs Red Hat's permission and the whole point is moot).

I believe what the license means to say is, "... without Red Hat asserting any copyright over the resulting program due to libcygwin.a/cygwin1.dll itself."

LGPL is compatible with Cygwin's license (GPL+exceptions)

Posted Nov 23, 2008 0:16 UTC (Sun) by vonbrand (guest, #4458) [Link]

The Red Hat people must have done their assignment before distributing the library under this license... and they are careful with legal stuff.

In any case, it is not the license which restricts distribution, it is copyright law. All the license does is allow you to do stuff the law forbids.