doc/README: mention about ARGS in do_cmake

Add an example on how to use ARGS to override cmake builds

Signed-off-by: Abhishek Lekshmanan <abhishek@suse.com>

diff --git a/README.md b/README.md
index ece373566bfb992e90f289925d00e06ed3f51812..d2a5d97f79bffa238502dcfe9e4c73dbc8214ffb 100644 (file)
--- a/README.md
+++ b/README.md
@@ -61,7 +61,11 @@ Build instructions:
 
 This assumes you make your build dir a subdirectory of the ceph.git
 checkout. If you put it elsewhere, just replace `..` in do_cmake.sh with a
-correct path to the checkout.
+correct path to the checkout. Any additional CMake args can be specified
+setting ARGS before invoking do_cmake. See [cmake options](#cmake-options) 
+for more details. Eg.
+
+    ARGS="-DCMAKE_C_COMPILER=gcc-7" ./do_cmake.sh
 
 To build only certain targets use: