1 Explaining the "No working init found." boot h !! 1 Explaining the dreaded "No init found." boot hang message
2 ============================================== 2 =========================================================
3 :Authors: Andreas Mohr <andi at lisas period d <<
4 Cristian Souza <cristianmsbr at gmai <<
5 3
6 This document provides some high-level reasons !! 4 OK, so you've got this pretty unintuitive message (currently located
7 (listed roughly in order of execution) to load !! 5 in init/main.c) and are wondering what the H*** went wrong.
8 !! 6 Some high-level reasons for failure (listed roughly in order of execution)
9 1) **Unable to mount root FS**: Set "debug" ke !! 7 to load the init binary are:
10 config file or CONFIG_CMDLINE) to get more !! 8
11 !! 9 A) Unable to mount root FS
12 2) **init binary doesn't exist on rootfs**: Ma !! 10 B) init binary doesn't exist on rootfs
13 root FS type (and ``root=`` kernel paramete !! 11 C) broken console device
14 partition), required drivers such as storag !! 12 D) binary exists but dependencies not available
15 USB!) and filesystem (ext3, jffs2, etc.) ar !! 13 E) binary cannot be loaded
16 modules, to be pre-loaded by an initrd). !! 14
17 !! 15 Detailed explanations:
18 3) **Broken console device**: Possibly a confl !! 16
19 --> initial console unavailable. E.g. some !! 17 A) Set "debug" kernel parameter (in bootloader config file or CONFIG_CMDLINE)
20 due to serial IRQ issues (e.g. missing inte !! 18 to get more detailed kernel messages.
>> 19 B) make sure you have the correct root FS type
>> 20 (and ``root=`` kernel parameter points to the correct partition),
>> 21 required drivers such as storage hardware (such as SCSI or USB!)
>> 22 and filesystem (ext3, jffs2 etc.) are builtin (alternatively as modules,
>> 23 to be pre-loaded by an initrd)
>> 24 C) Possibly a conflict in ``console= setup`` --> initial console unavailable.
>> 25 E.g. some serial consoles are unreliable due to serial IRQ issues (e.g.
>> 26 missing interrupt-based configuration).
21 Try using a different ``console= device`` o 27 Try using a different ``console= device`` or e.g. ``netconsole=``.
22 !! 28 D) e.g. required library dependencies of the init binary such as
23 4) **Binary exists but dependencies not availa !! 29 ``/lib/ld-linux.so.2`` missing or broken. Use
24 dependencies of the init binary such as ``/ !! 30 ``readelf -d <INIT>|grep NEEDED`` to find out which libraries are required.
25 broken. Use ``readelf -d <INIT>|grep NEEDED !! 31 E) make sure the binary's architecture matches your hardware.
26 are required. !! 32 E.g. i386 vs. x86_64 mismatch, or trying to load x86 on ARM hardware.
27 !! 33 In case you tried loading a non-binary file here (shell script?),
28 5) **Binary cannot be loaded**: Make sure the !! 34 you should make sure that the script specifies an interpreter in its shebang
29 your hardware. E.g. i386 vs. x86_64 mismatc !! 35 header line (``#!/...``) that is fully working (including its library
30 hardware. In case you tried loading a non-b !! 36 dependencies). And before tackling scripts, better first test a simple
31 you should make sure that the script specif !! 37 non-script binary such as ``/bin/sh`` and confirm its successful execution.
32 shebang header line (``#!/...``) that is fu !! 38 To find out more, add code ``to init/main.c`` to display kernel_execve()s
33 library dependencies). And before tackling !! 39 return values.
34 simple non-script binary such as ``/bin/sh` <<
35 execution. To find out more, add code ``to <<
36 kernel_execve()s return values. <<
37 40
38 Please extend this explanation whenever you fi 41 Please extend this explanation whenever you find new failure causes
39 (after all loading the init binary is a CRITIC 42 (after all loading the init binary is a CRITICAL and hard transition step
40 which needs to be made as painless as possible !! 43 which needs to be made as painless as possible), then submit patch to LKML.
41 Further TODOs: 44 Further TODOs:
42 45
43 - Implement the various ``run_init_process()`` 46 - Implement the various ``run_init_process()`` invocations via a struct array
44 which can then store the ``kernel_execve()`` 47 which can then store the ``kernel_execve()`` result value and on failure
45 log it all by iterating over **all** results 48 log it all by iterating over **all** results (very important usability fix).
46 - Try to make the implementation itself more h !! 49 - try to make the implementation itself more helpful in general,
47 providing additional error messages at affec !! 50 e.g. by providing additional error messages at affected places.
48 51
>> 52 Andreas Mohr <andi at lisas period de>
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