Add cmake select flag for HAL.

Signed-off-by: Ronan Le Martret <ronan.lemartret@iot.bzh>

1 files changed, 6 insertions, 0 deletions

diff --git a/README.md b/README.md
index 780da43..3efd127 100644
--- a/README.md
+++ b/README.md
@@ -13,4 +13,10 @@
     git submodule update --init
 ```
 
+## Build
 
+To activate a HAL, add "DHAL_XXX=1" HAL_XXX is the cmake build flag of the HAL.
+
+```bash
+cmake -DHAL_RCAR-M3=1
+```