[ale] huh ?...cannot use modules with GPLONLY symbols....

Joe Steele joe at madewell.com
Thu Nov 1 18:13:32 EST 2001

Joseph A Knapka wrote:

> What's considered "GPL compatible"? Can I still use
> modules with, say, a BSD or Artistic license? 

I wouldn't claim to know what's considered compatible, but there is 
this from linux/include/linux/module.h:

 * The following license idents are currently accepted as indicating free
 * software modules
 *      "GPL"                                [GNU Public License v2 or later]
 *      "GPL and additional rights"        [GNU Public License v2 rights and more]
 *      "Dual BSD/GPL"                        [GNU Public License v2 or BSD license choice]
 *      "Dual MPL/GPL"                        [GNU Public License v2 or Mozilla license choice]
 * The following other idents are available
 *      "Proprietary"                        [Non free products]
 * There are dual licensed components, but when running with Linux it is the
 * GPL that is relevant so this is a non issue. Similarly LGPL linked with GPL
 * is a GPL combined work.
 * This exists for several reasons
 * 1.   So modinfo can show license info for users wanting to vet their setup 
 *      is free
 * 2.   So the community can ignore bug reports including proprietary modules
 * 3.   So vendors can do likewise based on their own policies

> Are
> symbols exported by the kernel proper marked
> "GPL only"?

As I mentioned before, I don't find any kernel modules with GPL-only 
symbols.  Further, the ability to "EXPORT_SYMBOL_GPL" (defined in 
module.h) appears to me to be for use by modules, rather than kernel 

> I predict this change is going to precipitate a major
> FUD-storm among open-source foes, and probably
> conflict within the open-source community...
> It seems to me it now becomes harder for hardware
> manufacturers to support Linux while feeling "safe"
> about their investment in driver development. Not
> good, IMO. But IANAL, and maybe I misunderstand
> the point of this exercise.

The point of this exercise?  I have no idea.  One obvious thing is 
that it's unenforceable.  A developer is certainly free to write a 
GPL module that exports symbols for use only by other GPL modules.  
Likewise, an end user is free to modify that same GPL module so that 
its symbols are not restricted (The simplest defanging method, 
however, would be to make a minor change to module.h).  In fact, if a 
proprietary module developer was having problems because of the 
restrictions, he could defang the module himself and provide it to 
his customers.  The fact that the restrictions are unenforceable 
makes me wonder why a GPL developer would ever bother to make use of 


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