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In the vertex and fragment stages, the hardware is nice to us and leaves g0.2 zerod out for us so we can use it for headers. However, in compute, geometry, and tessellation stages, the hardware is not so nice. In particular, for compute shaders on BDW, the hardware places some debug bits in 23:15. As it happens, bit 15 is interpreted by the sampler as the alpha channel mask. This means that if you use a texturing instruction with a header in a compute shader, you may randomly get the alpha channel disabled. Since channel masks affect the return length of the sampler message, this can lead the GPU to expect a different mlen to the one you specified in the shader and this, in turn, hangs your GPU. Cc: "11.1" <mesa-stable@lists.freedesktop.org> Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
File: docs/README.WIN32 Last updated: 21 June 2013 Quick Start ----- ----- Windows drivers are build with SCons. Makefiles or Visual Studio projects are no longer shipped or supported. Run scons libgl-gdi to build gallium based GDI driver. This will work both with MSVS or Mingw. Windows Drivers ------- ------- At this time, only the gallium GDI driver is known to work. Source code also exists in the tree for other drivers in src/mesa/drivers/windows, but the status of this code is unknown. Recipe ------ Building on windows requires several open-source packages. These are steps that work as of this writing. - install python 2.7 - install scons (latest) - install mingw, flex, and bison - install pywin32 from here: http://www.lfd.uci.edu/~gohlke/pythonlibs get pywin32-218.4.win-amd64-py2.7.exe - install git - download mesa from git see http://www.mesa3d.org/repository.html - run scons General ------- After building, you can copy the above DLL files to a place in your PATH such as $SystemRoot/SYSTEM32. If you don't like putting things in a system directory, place them in the same directory as the executable(s). Be careful about accidentially overwriting files of the same name in the SYSTEM32 directory. The DLL files are built so that the external entry points use the stdcall calling convention. Static LIB files are not built. The LIB files that are built with are the linker import files associated with the DLL files. The si-glu sources are used to build the GLU libs. This was done mainly to get the better tessellator code. If you have a Windows-related build problem or question, please post to the mesa-dev or mesa-users list.