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