From 094d794af3ead79374fb23f5ea2ad9eda51c5adb Mon Sep 17 00:00:00 2001
From: Cliff Brake <cbrake@bec-systems.com>
Date: Tue, 9 Oct 2018 11:35:34 -0400
Subject: [PATCH] config and documentation on using busybox as init/dev/login

---
 conf/local.conf     |  5 +++++
 docs/init-system.md | 24 +++++++++++++++++++++---
 2 files changed, 26 insertions(+), 3 deletions(-)

diff --git a/conf/local.conf b/conf/local.conf
index a27ef29f3..1200f9f02 100644
--- a/conf/local.conf
+++ b/conf/local.conf
@@ -52,3 +52,8 @@ ENABLE_UART = "1"
 #VIRTUAL-RUNTIME_init_manager = "systemd"
 #DISTRO_FEATURES_BACKFILL_CONSIDERED = "sysvinit"
 #VIRTUAL-RUNTIME_initscripts = ""
+
+# Uncomment the following to enable busybox init/dev/login
+#VIRTUAL-RUNTIME_init_manager = "busybox"
+#VIRTUAL-RUNTIME_dev_manager = "busybox-mdev"
+#VIRTUAL-RUNTIME_login_manager = "busybox"
diff --git a/docs/init-system.md b/docs/init-system.md
index d0b6f3b59..41a7cf98d 100644
--- a/docs/init-system.md
+++ b/docs/init-system.md
@@ -1,5 +1,7 @@
 # Init System
 
+## Systemd
+
 SysVinit and Systemd are common init systems. SysVinit is the default, but Systemd can
 be enabled be adding the following to local.conf:
 
@@ -10,9 +12,28 @@ DISTRO_FEATURES_BACKFILL_CONSIDERED = "sysvinit"
 VIRTUAL-RUNTIME_initscripts = ""
 ```
 
+There is a significant size cost with systemd, so in some cases it may make sense to
+use sysvinit if image size is a priority.
+
+## Busybox Init
+
+Busybox can also be used as an init system with the following in local.conf:
+
+```
+VIRTUAL-RUNTIME_init_manager = "busybox"
+VIRTUAL-RUNTIME_dev_manager = "busybox-mdev"
+VIRTUAL-RUNTIME_login_manager = "busybox"
+```
+
+## Comparison of disk spaced used by init systems
+
 Systemd takes considerably more space than SysVinit. With a rPI2 build, the following
 are the rootfs sizes for core-image-minimal:
 
+* Busybox init/dev/login
+  * space used in ext4 filesystem on running system using df: 3.5MB
+  * adding sizes of files in image from buildhistory: 3.1MB
+  * number of files in image: 621
 * SysVinit
   * space used in ext4 filesystem on running system using df: 4.7MB
   * adding sizes of files in image from buildhistory: 4.3MB
@@ -21,6 +42,3 @@ are the rootfs sizes for core-image-minimal:
   * space used in ext4 filesystem on running system using df: 33.2MB
   * adding sizes of files in image from buildhistory: 22MB
   * number of files in image: 1,806
-
-There is a significant size cost with systemd, so in some cases it may make sense to
-use sysvinit if image size is a priority.