On Sat, Dec 10, 2011 at 03:13:06AM -0800, Mauro Carvalho Chehab wrote: > On 09-12-2011 20:50, Robert Morell wrote: > > On Mon, Dec 05, 2011 at 09:18:48AM -0800, Arnd Bergmann wrote: > >> On Friday 02 December 2011, Sumit Semwal wrote: > >>> This is the first step in defining a dma buffer sharing mechanism. > >> > > [...] > >> > >>> + return dmabuf; > >>> +} > >>> +EXPORT_SYMBOL(dma_buf_export); > >> > >> I agree with Konrad, this should definitely be EXPORT_SYMBOL_GPL, > >> because it's really a low-level function that I would expect > >> to get used by in-kernel subsystems providing the feature to > >> users and having back-end drivers, but it's not the kind of thing > >> we want out-of-tree drivers to mess with. > > > > Is this really necessary? If this is intended to be a > > lowest-common-denominator between many drivers to allow buffer sharing, > > it seems like it needs to be able to be usable by all drivers. > > > > If the interface is not accessible then I fear many drivers will be > > forced to continue to roll their own buffer sharing mechanisms (which is > > exactly what we're trying to avoid here, needless to say). > > Doing a buffer sharing with something that is not GPL is not fun, as, if any > issue rises there, it would be impossible to discover if the problem is either > at the closed-source driver or at the open source one. At the time I was using > the Nvidia proprietary driver, it was very common to have unexplained issues > caused likely by bad code there at the buffer management code, causing X > applications and extensions (like xv) to break. > > We should really make this EXPORT_SYMBOL_GPL(), in order to be able to latter > debug future share buffer issues, when needed. Sorry, I don't buy this argument. Making these exports GPL-only is not likely to cause anybody to open-source their driver, but will rather just cause them to use yet more closed-source code that is even less debuggable than this would be, to those without access to the source. Thanks, Robert > Regards, > Mauro -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>