Actually, some kernel developers believe that all exported symbols are contaminating, not just EXPORT_SYMBOL_GPL, see for example: http://thread.gmane.org/gmane

Actually, some kernel developers believe that all exported symbols are contaminating, not just EXPORT_SYMBOL_GPL, see for example: http://thread.gmane.org/gmane.linux.kernel/1390226/focus=1391147 http://thread.gmane.org/gmane.linux.kernel/1390226/focus=139... The test used by the industry for derivative works usually requires a full implementation of the same code with another OS than Linux (e.g the nvidia drivers which shares 95% of the codebase between Linux and Windows). Some ported-over-from-an-RTOS drivers fall into this as well, but there's rarely enough value in them that they shouldn't be opensourced. In the end there are so many nice features hidden behind EXPORT_SYMBOL_GPL that it's rarely worth it to go the proprietary route.