diff --git a/How-to-compile-DevTerm-CM3-Kernel.md b/How-to-compile-DevTerm-CM3-Kernel.md
index d1442c5..acfd417 100644
--- a/How-to-compile-DevTerm-CM3-Kernel.md
+++ b/How-to-compile-DevTerm-CM3-Kernel.md
@@ -1,3 +1,11 @@
+## Env 
+VirtualBox with ubuntu 20.04
+
+## Toolchain
+
+https://github.com/raspberrypi/tools/tree/master/arm-bcm2708/arm-rpi-4.9.3-linux-gnueabihf/bin
+
+
 ## Get kernel
 1. git://github.com/raspberrypi/linux.git
 1. git checkout remotes/origin/rpi-4.19.y