Update makefile syntax to EXTRA_CFLAGS

diff --git a/kmod/igb/README b/kmod/igb/README
index 2c77fe3..6e25db1 100644 (file)
--- a/kmod/igb/README
+++ b/kmod/igb/README
@@ -16,7 +16,7 @@ BUILDING
 
 The kernel igb module should be built which supports the latest Linux kernel
 3.x PTP clock support - to enable, execute make with -DIGB_PTP
-as a build option (e.g. make CFLAGS_EXTRA="-DIGB_PTP").
+as a build option (e.g. make EXTRA_CFLAGS="-DIGB_PTP").
 
 RUNNING