use init.d to start vanilla on boot

buildroot/configs/vanilla_raspberrypi0w_defconfig

@@ -4,7 +4,7 @@ BR2_TOOLCHAIN_EXTERNAL=y
 BR2_GLOBAL_PATCH_DIR="board/raspberrypi/patches"
 BR2_DOWNLOAD_FORCE_CHECK_HASHES=y
 BR2_ROOTFS_DEVICE_CREATION_DYNAMIC_EUDEV=y
-# BR2_ROOTFS_OVERLAY="$(BR2_EXTERNAL_VANILLA_PATH)/rootfs"
+BR2_ROOTFS_OVERLAY="$(BR2_EXTERNAL_VANILLA_PATH)/rootfs"
 BR2_ROOTFS_POST_BUILD_SCRIPT="board/raspberrypi0w/post-build.sh"
 BR2_ROOTFS_POST_IMAGE_SCRIPT="board/raspberrypi0w/post-image.sh"
 BR2_LINUX_KERNEL=y
@@ -14,6 +14,7 @@ BR2_LINUX_KERNEL_DEFCONFIG="bcmrpi"
 BR2_LINUX_KERNEL_DTS_SUPPORT=y
 BR2_LINUX_KERNEL_INTREE_DTS_NAME="broadcom/bcm2708-rpi-zero-w"
 BR2_LINUX_KERNEL_NEEDS_HOST_OPENSSL=y
+BR2_TARGET_GENERIC_GETTY=n
 BR2_PACKAGE_BUSYBOX_SHOW_OTHERS=y
 BR2_PACKAGE_XZ=y
 BR2_PACKAGE_MESA3D=y

buildroot/rootfs/etc/init.d/S99vanilla

@@ -0,0 +1,4 @@
+#!/bin/sh
+
+# Run Vanilla and send all stdout and stderr to /vanilla.log
+/usr/bin/vanilla > /vanilla.log 2>&1