title: How to check if /init starts /etc/inittab
body: <p>I have an embedded ARM system with processor AT91SAM9G45.</p>
  
  <p>System consists of two components:</p>
  
  <ol>
  <li>Linux kernel (4.14.79)</li>
  <li>Busybox 1.29.3 as initramfs image.</li>
  </ol>
  
  <p>I connect to the device using putty and connecting to serial port.</p>
  
  <p>When kernel starts, everything goes fine. Kernel unpacks initramfs image, all files are found and listed (I see it by debug messages). But when it starts /init, log messages are:</p>
  
  <pre><code>Freeing unused kernel memory: 384K
  This architecture does not have kernel memory protection.
  run_init_process BEFORE /init
  run_init_process AFTER /init, result = 0
  Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004
  </code></pre>
  
  <p>/init is symlink to /bin/busybox. I tried to replace /init with /sbin/init, /bin/busybox, /linuxrc, but results are the same.</p>
  
  <p>/etc/inittab file:</p>
  
  <pre><code># Begin /etc/inittab
  
  id::initdefault:
  
  si::sysinit:/etc/init.d/rc S
  
  #l0::wait:/etc/rc.d/init.d/rc 0
  #l1::wait:/etc/rc.d/init.d/rc 1
  #l2::wait:/etc/rc.d/init.d/rc 2
  #l3::wait:/etc/rc.d/init.d/rc 3
  #l4::wait:/etc/rc.d/init.d/rc 4
  #l5::wait:/etc/rc.d/init.d/rc 5
  #l6::wait:/etc/rc.d/init.d/rc 6
  
  ca::ctrlaltdel:/sbin/shutdown -t1 -a -r now
  
  su::once:/sbin/sulogin
  
  1::respawn:/sbin/getty ttyS1 115200
  2::respawn:/sbin/getty ttyS2 115200
  3::respawn:/sbin/getty ttyS3 115200
  4::respawn:/sbin/getty ttyS4 115200
  5::respawn:/sbin/getty ttyS5 115200
  6::respawn:/sbin/getty ttyS6 115200
  
  # End /etc/inittab
  </code></pre>
  
  <p>/etc/init.d/rcS file (this file is allowed to execute):</p>
  
  <pre><code>#!/bin/busybox sh
  echo "Hello world!"
  </code></pre>
  
  <p>I don't know if even /init process starts parsing /etc/inittab or it falls before getting /etc/inittab by some reasons I cannot find out. Maybe there are 
  some mistakes in my /etc/inittab and /etc/init.d/rcS files. Maybe there are some errors with terminal (/etc/init.d/rcS cannot write to stdout cause it's blocked, suspended, being used by another process and so on). </p>
  
  <p>How to definitely get sured, that /etc/inittab is started?</p>