49 lines
2.6 KiB
ReStructuredText
49 lines
2.6 KiB
ReStructuredText
Explaining the "No working init found." boot hang message
|
|
=========================================================
|
|
:Authors: Andreas Mohr <andi at lisas period de>
|
|
Cristian Souza <cristianmsbr at gmail period com>
|
|
|
|
This document provides some high-level reasons for failure
|
|
(listed roughly in order of execution) to load the init binary.
|
|
|
|
1) **Unable to mount root FS**: Set "debug" kernel parameter (in bootloader
|
|
config file or CONFIG_CMDLINE) to get more detailed kernel messages.
|
|
|
|
2) **init binary doesn't exist on rootfs**: Make sure you have the correct
|
|
root FS type (and ``root=`` kernel parameter points to the correct
|
|
partition), required drivers such as storage hardware (such as SCSI or
|
|
USB!) and filesystem (ext3, jffs2, etc.) are builtin (alternatively as
|
|
modules, to be pre-loaded by an initrd).
|
|
|
|
3) **Broken console device**: Possibly a conflict in ``console= setup``
|
|
--> initial console unavailable. E.g. some serial consoles are unreliable
|
|
due to serial IRQ issues (e.g. missing interrupt-based configuration).
|
|
Try using a different ``console= device`` or e.g. ``netconsole=``.
|
|
|
|
4) **Binary exists but dependencies not available**: E.g. required library
|
|
dependencies of the init binary such as ``/lib/ld-linux.so.2`` missing or
|
|
broken. Use ``readelf -d <INIT>|grep NEEDED`` to find out which libraries
|
|
are required.
|
|
|
|
5) **Binary cannot be loaded**: Make sure the binary's architecture matches
|
|
your hardware. E.g. i386 vs. x86_64 mismatch, or trying to load x86 on ARM
|
|
hardware. In case you tried loading a non-binary file here (shell script?),
|
|
you should make sure that the script specifies an interpreter in its
|
|
shebang header line (``#!/...``) that is fully working (including its
|
|
library dependencies). And before tackling scripts, better first test a
|
|
simple non-script binary such as ``/bin/sh`` and confirm its successful
|
|
execution. To find out more, add code ``to init/main.c`` to display
|
|
kernel_execve()s return values.
|
|
|
|
Please extend this explanation whenever you find new failure causes
|
|
(after all loading the init binary is a CRITICAL and hard transition step
|
|
which needs to be made as painless as possible), then submit a patch to LKML.
|
|
Further TODOs:
|
|
|
|
- Implement the various ``run_init_process()`` invocations via a struct array
|
|
which can then store the ``kernel_execve()`` result value and on failure
|
|
log it all by iterating over **all** results (very important usability fix).
|
|
- Try to make the implementation itself more helpful in general, e.g. by
|
|
providing additional error messages at affected places.
|
|
|