title: Does any OpenCL host have more than one platform?
body: <p>The definition of a platform in Khronos' OpenCL 1.0 and 1.1 <a href="http://www.khronos.org/registry/cl/" rel="noreferrer">specification</a>:</p>
  
  <blockquote>
    <p>Platform: The host plus a collection of devices managed by the OpenCL framework that allow an application to share resources and execute kernels on devices in the platform.</p>
  </blockquote>
  
  <p>The OpenCL function <a href="http://www.khronos.org/registry/cl/sdk/1.0/docs/man/xhtml/clGetPlatformIDs.html" rel="noreferrer">clGetPlatformIDs</a> creates an array of platforms, implying that multiple platforms are possible.  Is it safe to assume that a given OpenCL host has only one platform?</p>
  
  <p>In other words, will I lose anything on any host by doing this:</p>
  
  <pre><code>cl_platform_id platform_id;
  cl_uint num_platforms;
  errcode = clGetPlatformIDs(1, &amp;platform_id, &amp;num_platforms);
  </code></pre>