On the value of EXPORT_SYMBOL_GPL
Posted Oct 6, 2005 11:38 UTC (Thu) by dwmw2
In reply to: On the value of EXPORT_SYMBOL_GPL
Parent article: On the value of EXPORT_SYMBOL_GPL
If your module is non-GPL then obviously it very much matters whether it is a derived work of the GPL-ed Linux kernel!
Very true. But remember -- the GPL speaks not only of 'derived' works, but also of 'collective' works. Consider section 2 of the GPL:
If [your modules] are not derived from the [kernel], and can reasonably be considered independent and separate works in themselves, then this License, and its terms, do not apply to those [modules] when you distribute them as separate works.
But when you distribute those same [modules] as part of a whole which is a work based on the [kernel], the distribution of the whole must be on the terms of this License, whose permissions for other licensees extend to the entire whole, and thus to each and every part regardless of who wrote it.
Thus, it is not the intent of this section to claim rights or contest your rights to work written entirely by you; rather, the intent is to exercise the right to control the distribution of derivative or collective works based on the [kernel]
So while what Ingo said was true, it wasn't quite complete. Not only does it matter whether your module is a derivative work, it also
matters if your module is part of a collective work.
Examples of a collective work with both GPL'd sections and sections which would otherwise be unaffected by the GPL:
- A tarball containing both Linux-specific GPL'd 'wrapper' code and also binary blob or 'HAL'
- Firmware for an embedded Linux device, containing both the kernel itself and also some Ethernet driver modules
In each of these cases, the fact that the binary blob is distributed as part of a larger whole is very important, despite the fact that in itself
it isn't a derived
work. The binary blob is still
covered by the GPL, because of the nature of the distribution.
We should probably try to stop using the term 'derived work' as if it's synonymous with 'GPL-affected'. The GPL actually goes a lot further than that.
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