Intel cards have both classic and gallium mesa drivers and the classic version can use XvMC. However, currently mesa-8.0 USE-flag 'xvmc' requires 'g3dvl', which requires 'gallium', which is wrong. To be more specific: I have i915 Intel card and very happy with classic drivers, so I don't need gallium stuff at all; also classic driver for i915 provides XvMC libs. But with 'xvmc' USE-flag enabled I have to enable also 'gallium' USE-flag, which I don't really need at all. Steps to reproduce: 1. try to emerge media-libs/mesa-8.0 with 'xvmc' and 'classic' enabled and 'gallium' disabled and VIDEO_CARDS="intel" 2. See 'REQUIRED_USE flag constraints are unsatisfied' error message. Expected results: Sucessfull build and install.
The XvMC USE flag for Mesa is enabling the Gallium3D Video Decode Layer's support for XvMC, in the same way that the vdpau USE flag enables its VDPAU support. Enabling XvMC with the classic driver doesn't actually enable anything. The xf86-video-intel DDX provides XvMC, so you have XvMC whether you're using Gallium3D or not.
Thank you very much for your explanation and quick response.
