Based on kernel version 4.16.1. Page generated on 2018-04-09 11:52 EST.
1 Explaining the dreaded "No init found." boot hang message 2 ========================================================= 3 4 OK, so you've got this pretty unintuitive message (currently located 5 in init/main.c) and are wondering what the H*** went wrong. 6 Some high-level reasons for failure (listed roughly in order of execution) 7 to load the init binary are: 8 9 A) Unable to mount root FS 10 B) init binary doesn't exist on rootfs 11 C) broken console device 12 D) binary exists but dependencies not available 13 E) binary cannot be loaded 14 15 Detailed explanations: 16 17 A) Set "debug" kernel parameter (in bootloader config file or CONFIG_CMDLINE) 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). 27 Try using a different ``console= device`` or e.g. ``netconsole=``. 28 D) e.g. required library dependencies of the init binary such as 29 ``/lib/ld-linux.so.2`` missing or broken. Use 30 ``readelf -d <INIT>|grep NEEDED`` to find out which libraries are required. 31 E) make sure the binary's architecture matches your hardware. 32 E.g. i386 vs. x86_64 mismatch, or trying to load x86 on ARM hardware. 33 In case you tried loading a non-binary file here (shell script?), 34 you should make sure that the script specifies an interpreter in its shebang 35 header line (``#!/...``) that is fully working (including its library 36 dependencies). And before tackling scripts, better first test a simple 37 non-script binary such as ``/bin/sh`` and confirm its successful execution. 38 To find out more, add code ``to init/main.c`` to display kernel_execve()s 39 return values. 40 41 Please extend this explanation whenever you find new failure causes 42 (after all loading the init binary is a CRITICAL and hard transition step 43 which needs to be made as painless as possible), then submit patch to LKML. 44 Further TODOs: 45 46 - Implement the various ``run_init_process()`` invocations via a struct array 47 which can then store the ``kernel_execve()`` result value and on failure 48 log it all by iterating over **all** results (very important usability fix). 49 - try to make the implementation itself more helpful in general, 50 e.g. by providing additional error messages at affected places. 51 52 Andreas Mohr <andi at lisas period de>