I'm trying to port a small GL program that I've been working on from Linux to Windows. I have the following:

window_ = SDL_CreateWindow(...);
SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, SDL_GL_CONTEXT_DEBUG_FLAG);
glContext_ = SDL_GL_CreateContext(window_);
glewInit();
if (GLEW_ARB_debug_output)
{
    glDebugMessageCallbackARB(&DebugCallback, nullptr);
}

I was surprised to find out that GLEW_ARB_debug_output evaluates to false. Could it be that ARB_debug_output not supported on Windows, with the latest drivers for my video card (an older Radeon HD540v)? Am I doing anything wrong? I thought this extension was rather old, and it would probably be supported everywhere by now.

Update: I added my SDL initialization code, as I needed to pass SDL_GL_CONTEXT_DEBUG_FLAG. Unfortunately, ARB_debug_output is still not supported.

Update: After initializing the context with the debug flag through SDL, I manually queried the available extensions (bypassing GLEW) and ARB_debug_output is not available! Again, could this not be supported on my implementation?