On Tue, Oct 11, 2011 at 10:23 AM, Sumit Semwal <sumit.semwal@xxxxxx> wrote: > This is the first step in defining a dma buffer sharing mechanism. > > A new buffer object dma_buf is added, with operations and API to allow easy > sharing of this buffer object across devices. > > The framework allows: > - a new buffer-object to be created with fixed size. > - different devices to 'attach' themselves to this buffer, to facilitate > backing storage negotiation, using dma_buf_attach() API. > - association of a file pointer with each user-buffer and associated > allocator-defined operations on that buffer. This operation is called the > 'export' operation. > - this exported buffer-object to be shared with the other entity by asking for > its 'file-descriptor (fd)', and sharing the fd across. > - a received fd to get the buffer object back, where it can be accessed using > the associated exporter-defined operations. > - the exporter and user to share the scatterlist using get_scatterlist and > put_scatterlist operations. > > Atleast one 'attach()' call is required to be made prior to calling the > get_scatterlist() operation. > > Couple of building blocks in get_scatterlist() are added to ease introduction > of sync'ing across exporter and users, and late allocation by the exporter. > > mmap() file operation is provided for the associated 'fd', as wrapper over the > optional allocator defined mmap(), to be used by devices that might need one. Why is this needed? it really doesn't make sense to be mmaping objects independent of some front-end like drm or v4l. how will you know what contents are in them, how will you synchronise access. Unless someone has a hard use-case for this I'd say we drop it until someone does. Dave. -- 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