Build.md

 
 # Introduction
 
-Likwid is built using GNU make and Perl. Besides the Linux kernel and the standard C library, all required dependencies are shipped with the archive ([Lua](http://www.lua.org/) and [hwloc](http://www.open-mpi.org/projects/hwloc/)). It should build on any Linux distribution with a recent GCC or CLANG compiler and 2.6 or newer Linux kernel without any changes.
+Likwid is built using GNU make and Perl. Besides the Linux kernel and the standard C library, all required dependencies are shipped with the archive ([Lua](http://www.lua.org/) and [hwloc](http://www.open-mpi.org/projects/hwloc/)) and [GOTCHA](https://github.com/LLNL/GOTCHA) (for NVIDIA GPU support, see [here](http://www.asd.de)). It should build on any Linux distribution with a recent GCC or CLANG compiler and 2.6 or newer Linux kernel without any changes.
 
 There is one generic top level Makefile and one .mk configuration file for each
 compiler (at the moment GCC, CLANG and ICC). Please note that we test LIKWID only with GCC. CLANG and ICC is only tested for basic functionality.    
@@ -10,6 +10,8 @@ There is one exception: If you want to use LIKWID on a Intel Xeon Phi card (KNC)
 to choose the MIC as Compiler in `config.mk`, which is based on Intel ICC compiler.
 
 
+
+
 # Directory structure
 
 All source files are in the *src* directory. All header files are located in
@@ -73,6 +75,7 @@ Although we tried to minimize the external dependencies of LIKWID, some advanced
 - [[likwid-agent|likwid-agent]] provided multiple backends to output the periodically measured data. The syslog backend requires the shell tool `logger` to be installed. The [RRD](https://oss.oetiker.ch/rrdtool/) backend requires `rrdtool` and the GMetric backend the `gmetric` tool, part of the [Ganglia Monitoring System](http://ganglia.sourceforge.net/).
 - In order to create the HTML documentation of LIKWID, the tool [Doxygen](www.doxygen.org) is required.
 
+
 # Build targets
 
 You have to edit `config.mk` to configure your build and install path.
@@ -155,3 +158,7 @@ LIKWID in direct or accessdaemon mode uses the common MSR and PCI interfaces fro
 
 # LIKWID as static library
 If you want to compile LIKWID as static library, you have to set `SHARED_LIBRARY` in `config.mk` to false. You can integrate LIKWID in your application but you cannot use the command line tools (except likwid-bench). I havn't found a way to make the tools work because they are written in Lua and in order to load a C-library at runtime, Lua needs dlopen which only works with shared libraries.
+
+# LIKWID with NVIDIA GPU support
+In order to build LIKWID with support for NVIDIA GPUs, you have to change `NVIDIA_INTERFACE` in `config.mk`to `true`. The Makefile uses the environment variable `CUDA_HOME` to determine the paths for the compilations but if needed, you can adjust the paths manually in `CUDAINCLUDE` and `CUPTIINCLUDE`. In case of problems, rebuild (`make distclean && make`) with `BUILDAPPDAEMON` set to `true`.
+At runtime, LIKWID uses `dlopen`to load the required functions, so the library paths to CUDA and CUPTI should be in `LD_LIBRARY_PATH`.
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