Laurent Pinchart laurent.pinchart at ideasonboard.com
Thu Oct 11 05:52:41 PDT 2012

Hi Hans,

On Thursday 11 October 2012 13:36:45 Hans Verkuil wrote:
> On Thu 11 October 2012 13:34:07 Alan Cox wrote:
> > > The whole purpose of this API is to let DRM and V4L drivers share
> > > buffers for zero-copy pipelines. Unfortunately it is a fact that
> > > several popular DRM drivers are closed source. So we have a choice
> > > between keeping the export symbols GPL and forcing those closed-source
> > > drivers to make their own incompatible API, thus defeating the whole
> > > point of DMABUF, or using EXPORT_SYMBOL and letting the closed source
> > > vendors worry about the legality. They are already using such functions
> > > (at least nvidia is), so they clearly accept that risk.
> > 
> > Then they can accept the risk of ignoring EXPORT_SYMBOL_GPL and
> > calling into it anyway can't they. Your argument makes no rational sense
> > of any kind.
> Out of curiosity: why do we have both an EXPORT_SYMBOL and an
> EXPORT_SYMBOL_GPL if there is no legal difference?
> And if there is a difference between the two, then what is it?

As far as I understand, EXPORT_SYMBOL_GPL means "I consider closed-source 
kernel modules as a GPL violation, you can have a different opinion, but then 
don't use my APIs".


Laurent Pinchart

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