Originally Posted by
scaryjim
I highly doubt it will be open source, but the rumour is that it will be an open API - that is, AMD will publish the specifications, which should allow nvidia (and intel/via/other graphics manufacturers, should they so choose) to write drivers that will respond to Mantle API calls as well as DX ones. But since AMD will control Mantle, the chances are it will always work better on AMD hardware as they'll always be ahead of the development curve in terms of the drivers and API development.
Of course, if AMD want Mantle to be truly cross-platform they will need to look at the Linux world, and either massively improve their binary blob drivers or start fully supporting the open-source drivers. And if they did the latter it would give their competitors a fairly detailed look into the internal workings of Mantle anyway...