Merge pull request kubernetes#7 from s-urbaniak/readme

README: add more buildroot instruction

README.md

@@ -7,6 +7,26 @@ It includes:
 - rkt
 - docker
 
+## Quickstart
+
+To use this ISO image, use the `--iso-url` flag in minikube:
+
+```
+$ minikube start --iso-url=https://github.com/coreos/minikube-iso/releases/download/v0.0.1/minikube-v0.0.1.iso
+```
+
+To test the minikube rkt container runtime support, make sure you have a locally built version of minikube including https://github.com/kubernetes/minikube/pull/511, and execute:
+
+```
+$ cd $HOME/src/minikube/src/k8s.io/minikube
+$ ./out/mininikube start \
+    --container-runtime=rkt \
+    --kubernetes-version=file://$HOME/minikube/src/k8s.io/minikube/out/localkube \
+    --iso-url=https://github.com/coreos/minikube-iso/releases/download/v0.0.1/minikube-v0.0.1.iso
+```
+
+## Hacking
+
 ### Build instructions
 ```
 $ cd $HOME
@@ -22,20 +42,51 @@ The bootable ISO image will be available in `output/images/rootfs.iso9660`.
 
 **Note**: This is currently intended to be a stop-gap solution. In the middleterm this is meant to be replaced by a "slim" version of a bootable CoreOS image.
 
-## Quickstart
+### Buildroot configuration
 
-To use this ISO image, use the `--iso-url` flag in minikube:
+To change the buildroot configuration, execute:
 
 ```
-$ minikube start --iso-url=https://github.com/coreos/minikube-iso/releases/download/v0.0.1/minikube-v0.0.1.iso
+$ cd buildroot
+$ make menuconfig
+$ make
 ```
 
-To test the minikube rkt container runtime support, make sure you have a locally built version of minikube including https://github.com/kubernetes/minikube/pull/511, and execute:
+To change the kernel configuration, execute:
 
 ```
-$ cd $HOME/src/minikube/src/k8s.io/minikube
-$ ./out/mininikube start \
-    --container-runtime=rkt \
-    --kubernetes-version=file://$HOME/minikube/src/k8s.io/minikube/out/localkube \
-    --iso-url=https://github.com/coreos/minikube-iso/releases/download/v0.0.1/minikube-v0.0.1.iso
+$ cd buildroot
+$ make linux-menuconfig
+$ make
+```
+
+The last commands copies changes made to the kernel configuration to the minikube-iso defconfig.
+
+### Saving buildroot/kernel configuration changes
+
+To save any buildroot configuration changes made with `make menuconfig`, execute:
+
 ```
+$ cd buildroot
+$ make savedefconfig
+```
+
+The changes will be reflected in the `minikube-iso/configs/minikube_defconfig` file.
+
+```
+$ cd minikube-iso
+$ git stat
+## master
+ M configs/minikube_defconfig
+```
+
+To save any kernel configuration changes made with `make linux-menuconfig`, execute:
+
+```
+$ cd buildroot
+$ make linux-savedefconfig
+$ cp output/build/linux-4.7.2/defconfig \
+    ../minikube-iso/board/coreos/minikube/linux-4.7_defconfig
+```
+
+The changes will be reflected in the `minikube-iso/configs/minikube_defconfig` file.