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       libOpenCL, - OCL-ICD implementation	of OpenCL ICD loader

DESCRIPTION is the library linked by OpenCL programs. It does not
       contains	any OpenCL implementation itself, but merly act	as a
       dispatcher to real OpenCL implementations provided as OpenCL
       Installable Client Driver (ICD).	An ICD loader should be	able to	load
       ICDs provided by	any vendors.

       The ICD Loader looks for	files into /usr/local/etc/OpenCL/vendors
       directory and, for each file whose name ends with .icd, the ICD Loader
       loads with dlopen(3) the	shared library whose name is on	the first line
       of the .icd file. According to OpenCL specifications from Khronos (see
       [Khronos]), the default path for	this purpose is
       /usr/local/etc/OpenCL/vendors, but this OCL-ICD version has been
       configurated otherwise.

       Each shared library name	in ".icd" files	can have its path, or it can
       be a plain filename. In the latter case,	the ICD	shared library will be
       looked for into the standard dynamic library loader paths.

       Some environment	variables can be used modify the default behavior of

	   This	variable allows	one to modify the default
	   /usr/local/etc/OpenCL/vendors path. It is compatible	with some
	   other ICD loaders (but not all of them, as the variable is not part
	   of the standard). Note that $OCL_ICD_VENDORS	(see below) is used in
	   priority if defined and not empty.

	   This	variable allows	one to change the way ICD are searched on the
	   system. Several cases are considered:

	    1. if $OCL_ICD_VENDORS is a	directory path,	then this path
	       replaces	the "/usr/local/etc/OpenCL/vendors" path in the
	       standard	behavior: the loader will use the .icd files in	this

	    2. else, if	$OCL_ICD_VENDORS ends with .icd, will
	       only load the ICD whose shared library name is wrote into the
	       specified ".icd"	file;

	       If there	is no slashes into $OCL_ICD_VENDORS, will
	       first try to use	/usr/local/etc/OpenCL/vendors/$OCL_ICD_VENDORS
	       is defined). If this fail or if there are shashes, it uses
	       $OCL_ICD_VENDORS	(as a relative or absolute file	name path).

	    3. else will try to load $OCL_ICD_VENDORS as the ICD
	       shared library itself (i.e. to load it directly with

	   If set to an	non-empty value, contrary the Khronos specification,
	   the loader will not check that the loaded ICDs declare the
	   cl_khr_icd extension. It will also use the clGetPlatformInfo	from
	   the dispatch	table if no such function is globally available. You
	   may need to define this environment variable	if you are using not
	   (fully) compliant ICD, or if	you are	using the Intel	ICD together
	   with	optirun(1). In the latter case,	a bug into the Intel ICD will
	   make	the application	crash.

       If set to the debug value, some additional messages will	be printed in
       debug mode (see OCL_ICD_DEBUG below).

	   Allows one to choose	the way	platforms are sorted when presented to
	   programs through clGetPlatformIDs(3). Current provided algorithms

	   o   devices:	first, list platforms that support most	GPU, then most
	       CPU then	most accelerators. If OCL_ICD_PLATFORM_SORT is not set
	       or set to an unknown value, this	algorithm is used.

	   o   none: no	sort is	done and the order can change at each run.

	   Number of the platform to choose as default platform. Note that
	   using this environment variable without ensuring the	use of a sort
	   algorithm for platforms is not really useful.

	   If ocl-icd has been compiled	with debug support, you	can set	this
	   environment variable	to a value where each bit display some kind of
	   informations. Defined values	are:

	   o   1: warnings (enabled by default if debug	support	is present and
	       OCL_ICD_DEBUG is	not set)

	   o   2: informative messages

	   o   4: entering/exiting for some OpenCL functions

	   o   8: dump of the internal structure of loaded ICDs

	   OCL_ICD_DEBUG is mainly useful for ocl-icd development itself
	   and/or for ICD development.

       Khronos OpenCL registry website

       Vincent Danjean <>

				  2015-06-08			  LIBOPENCL(7)


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