[Mesa-dev] Wrong colors in 3D apps on big-endian systems

[Michel Dänzer]

On Sam, 2014-03-08 at 01:34 +0100, Christian Zigotzky wrote:
> Hi All,
> 
> I have figured out that the following definitions are not necessary for 
> big-endian systems in the file "src/gallium/include/pipe/p_format.h":
> 
> #if defined(PIPE_ARCH_LITTLE_ENDIAN)
> #define PIPE_FORMAT_RGBA8888_UNORM PIPE_FORMAT_R8G8B8A8_UNORM
> #define PIPE_FORMAT_RGBX8888_UNORM PIPE_FORMAT_R8G8B8X8_UNORM
> #define PIPE_FORMAT_BGRA8888_UNORM PIPE_FORMAT_B8G8R8A8_UNORM
> #define PIPE_FORMAT_BGRX8888_UNORM PIPE_FORMAT_B8G8R8X8_UNORM
> #define PIPE_FORMAT_ARGB8888_UNORM PIPE_FORMAT_A8R8G8B8_UNORM
> #define PIPE_FORMAT_XRGB8888_UNORM PIPE_FORMAT_X8R8G8B8_UNORM
> #define PIPE_FORMAT_ABGR8888_UNORM PIPE_FORMAT_A8B8G8R8_UNORM
> #define PIPE_FORMAT_XBGR8888_UNORM PIPE_FORMAT_X8B8G8R8_UNORM
> #elif defined(PIPE_ARCH_BIG_ENDIAN)
> #define PIPE_FORMAT_ABGR8888_UNORM PIPE_FORMAT_R8G8B8A8_UNORM
> #define PIPE_FORMAT_XBGR8888_UNORM PIPE_FORMAT_R8G8B8X8_UNORM
> #define PIPE_FORMAT_XRGB8888_UNORM PIPE_FORMAT_B8G8R8X8_UNORM
> #define PIPE_FORMAT_ARGB8888_UNORM PIPE_FORMAT_B8G8R8A8_UNORM
> #define PIPE_FORMAT_XRGB8888_UNORM PIPE_FORMAT_B8G8R8X8_UNORM
> #define PIPE_FORMAT_BGRA8888_UNORM PIPE_FORMAT_A8R8G8B8_UNORM
> #define PIPE_FORMAT_BGRX8888_UNORM PIPE_FORMAT_X8R8G8B8_UNORM
> #define PIPE_FORMAT_RGBA8888_UNORM PIPE_FORMAT_A8B8G8R8_UNORM
> #define PIPE_FORMAT_RGBX8888_UNORM PIPE_FORMAT_X8B8G8R8_UNORM
> #endif
> 
> This definitions for big-endian systems are responsible for the wrong 
> colors problem. I have commented out the big-endian definitions.
> 
> //#if defined(PIPE_ARCH_LITTLE_ENDIAN)
> #define PIPE_FORMAT_RGBA8888_UNORM PIPE_FORMAT_R8G8B8A8_UNORM
> #define PIPE_FORMAT_RGBX8888_UNORM PIPE_FORMAT_R8G8B8X8_UNORM
> #define PIPE_FORMAT_BGRA8888_UNORM PIPE_FORMAT_B8G8R8A8_UNORM
> #define PIPE_FORMAT_BGRX8888_UNORM PIPE_FORMAT_B8G8R8X8_UNORM
> #define PIPE_FORMAT_ARGB8888_UNORM PIPE_FORMAT_A8R8G8B8_UNORM
> #define PIPE_FORMAT_XRGB8888_UNORM PIPE_FORMAT_X8R8G8B8_UNORM
> #define PIPE_FORMAT_ABGR8888_UNORM PIPE_FORMAT_A8B8G8R8_UNORM
> #define PIPE_FORMAT_XBGR8888_UNORM PIPE_FORMAT_X8B8G8R8_UNORM
> //#elif defined(PIPE_ARCH_BIG_ENDIAN)
> //#define PIPE_FORMAT_ABGR8888_UNORM PIPE_FORMAT_R8G8B8A8_UNORM
> //#define PIPE_FORMAT_XBGR8888_UNORM PIPE_FORMAT_R8G8B8X8_UNORM
> //#define PIPE_FORMAT_XRGB8888_UNORM PIPE_FORMAT_B8G8R8X8_UNORM
> //#define PIPE_FORMAT_ARGB8888_UNORM PIPE_FORMAT_B8G8R8A8_UNORM
> //#define PIPE_FORMAT_XRGB8888_UNORM PIPE_FORMAT_B8G8R8X8_UNORM
> //#define PIPE_FORMAT_BGRA8888_UNORM PIPE_FORMAT_A8R8G8B8_UNORM
> //#define PIPE_FORMAT_BGRX8888_UNORM PIPE_FORMAT_X8R8G8B8_UNORM
> //#define PIPE_FORMAT_RGBA8888_UNORM PIPE_FORMAT_A8B8G8R8_UNORM
> //#define PIPE_FORMAT_RGBX8888_UNORM PIPE_FORMAT_X8B8G8R8_UNORM
> //#endif
> 
> And Mesa 10.1.0 works with the right colors on my PPC Linux system.

Congratulations, you just broke llvmpipe again on big endian systems. ;)
Did you even look at the commits introducing those defines? Did you
really think those defines, with explicit endianness checks, were
introduced for no reason but to break drivers on big endian systems?


I explained the problem in r600g and how it could be solved. Please
explore that.


-- 
Earthling Michel Dänzer            |                  http://www.amd.com
Libre software enthusiast          |                Mesa and X developer