Add more information into Readme file

Change-Id: Id3e484877eaf8123ad6c767caa5f3546c02f5d98

opencl/README.md

@@ -1,18 +1,61 @@
-# ROCm OpenCL™ Runtime
+# OpenCL™ Compatible Runtime
 
-Please build/install ROCclr first.
+-   OpenCL 2.0 compatible language runtime
+-   Supports offline and in-process/in-memory compilation
 
-  Please view build steps here:
-  https://github.com/ROCm-Developer-Tools/ROCclr
+## Getting the source code
+Download the git projects using the following commands:
 
-## Building OpenCL
+```bash
+git clone -b master-next https://github.com/RadeonOpenCompute/ROCm-OpenCL-Runtime.git
+```
 
-cd $OPENCL_DIR
+## Repository branches
+The repository maintains several branches. The branches that are of importance are:
 
+-    master-next: This is the default branch.
+
+## Setup OpenCL
+Copy the amdocl64.icd file to /etc/OpenCL/vendors
+
+```bash
+sudo cp api/opencl/config/amdocl64.icd /etc/OpenCL/vendors/
+```
+
+## Building
+Follow these steps:
+
+-   Build ROCclr first. Follow the steps in the following link to build ROCclr
+   [ROCclr Readme](https://github.com/ROCm-Developer-Tools/ROCclr)
+   In this step, $OPENCL_DIR and $ROCclr_DIR are defined.
+
+-   Building OpenCL
+Run these commands:
+
+```bash
+cd "$OPENCL_DIR"
 mkdir -p build; cd build
+cmake -DUSE_COMGR_LIBRARY=ON -DCMAKE_PREFIX_PATH="$ROCclr_DIR/build" ..
+make -j$(nproc)
+```
 
-cmake -DCMAKE_PREFIX_PATH=/path/to/rocclr/build/or/install ..
+For release build, add "-DCMAKE_BUILD_TYPE=Release" to the cmake command line.
 
-make
+### Obsolete
+These building instructions should be used for ROCm 3.5 release branch and earlier.
 
+```bash
+cd $OPENCL_DIR
+mkdir -p build; cd build
+cmake -DVDI_DIR="$ROCclr_DIR" -DLIBVDI_STATIC_DIR="$ROCclr_DIR/build" ..
+make -j$(nproc)
+```
 
+Previously, the environment variable VDI_DIR was defined in [ROCclr](https://github.com/ROCm-Developer-Tools/ROCclr). We did not use environment variable ROCclr_DIR. The cmake command was:
+
+```bash
+cmake -DVDI_DIR="$VDI_DIR" -DLIBVDI_STATIC_DIR="$VDI_DIR/build" ..
+```
+
+---
+OpenCL™ is registered Trademark of Apple