From fc168d6eb549a5846aac798c61b3670a6074b37d Mon Sep 17 00:00:00 2001
From: Ciro Santilli <ciro.santilli@gmail.com>
Date: Fri, 9 Feb 2018 20:48:45 +0000
Subject: [PATCH] Add init_env_poweroff.sh

---
 README.md                           |  1 +
 init.md                             | 17 +++++++++++++++--
 rootfs_overlay/init_env_poweroff.sh |  4 ++++
 3 files changed, 20 insertions(+), 2 deletions(-)
 create mode 100755 rootfs_overlay/init_env_poweroff.sh

diff --git a/README.md b/README.md
index abd170b..22578de 100644
--- a/README.md
+++ b/README.md
@@ -45,6 +45,7 @@ See the [getting started section](getting-started.md) for further details.
         1.  [KGDB](kgdb.md)
         1.  [gdbserver](gdbserver.md)
     1.  [Other architectures](other-architectures.md)
+    1.  [init](init.md)
     1.  [modprobe](modprobe.md)
     1.  [X11](x11.md)
     1.  [Count boot instructions](count-boot-instructions.md)
diff --git a/init.md b/init.md
index b196c79..eb388cf 100644
--- a/init.md
+++ b/init.md
@@ -14,7 +14,7 @@ systemd is a "popular" `/init` implementation for desktop distros as of 2017.
 
 BusyBox provides its own minimalistic init implementation which Buildroot uses by default.
 
-### Custom init
+## Custom init
 
 Is the default BusyBox `/init` too bloated for you, minimalism freak?
 
@@ -31,7 +31,7 @@ Also remember that if your init returns, the kernel will panic, there are just t
 - run forever in a loop or long sleep
 - `poweroff` the machine
 
-### Disable networking
+## Disable networking
 
 The default BusyBox init scripts enable networking, and there is a 15 second timeout in case your network is down or if your kernel / emulator setup does not support it.
 
@@ -42,3 +42,16 @@ To disable networking, use:
 To restore it, run:
 
     ./build -t initscripts-reconfigure
+
+## The init environment
+
+The docs make it clear https://www.kernel.org/doc/html/v4.14/admin-guide/kernel-parameters.html
+
+> The kernel parses parameters from the kernel command line up to “–”;
+> if it doesn’t recognize a parameter and it doesn’t contain a ‘.’, the parameter gets passed to init:
+> parameters with ‘=’ go into init’s environment, others are passed as command line arguments to init.
+> Everything after “–” is passed as an argument to init.
+
+And you can try it out with:
+
+    ./run -e 'init=/init_env_poweroff.sh - asdf=qwer zxcv' -n
diff --git a/rootfs_overlay/init_env_poweroff.sh b/rootfs_overlay/init_env_poweroff.sh
new file mode 100755
index 0000000..5c10aaa
--- /dev/null
+++ b/rootfs_overlay/init_env_poweroff.sh
@@ -0,0 +1,4 @@
+#!/bin/sh
+echo "$@"
+env
+/poweroff.out