1*7dbffd3fSCristian SouzaExplaining the "No working init found." boot hang message 29d85025bSMauro Carvalho Chehab========================================================= 3*7dbffd3fSCristian Souza:Authors: Andreas Mohr <andi at lisas period de> 4*7dbffd3fSCristian Souza Cristian Souza <cristianmsbr at gmail period com> 59d85025bSMauro Carvalho Chehab 6*7dbffd3fSCristian SouzaThis document provides some high-level reasons for failure 7*7dbffd3fSCristian Souza(listed roughly in order of execution) to load the init binary. 89d85025bSMauro Carvalho Chehab 9*7dbffd3fSCristian Souza1) **Unable to mount root FS**: Set "debug" kernel parameter (in bootloader 10*7dbffd3fSCristian Souza config file or CONFIG_CMDLINE) to get more detailed kernel messages. 119d85025bSMauro Carvalho Chehab 12*7dbffd3fSCristian Souza2) **init binary doesn't exist on rootfs**: Make sure you have the correct 13*7dbffd3fSCristian Souza root FS type (and ``root=`` kernel parameter points to the correct 14*7dbffd3fSCristian Souza partition), required drivers such as storage hardware (such as SCSI or 15*7dbffd3fSCristian Souza USB!) and filesystem (ext3, jffs2, etc.) are builtin (alternatively as 16*7dbffd3fSCristian Souza modules, to be pre-loaded by an initrd). 179d85025bSMauro Carvalho Chehab 18*7dbffd3fSCristian Souza3) **Broken console device**: Possibly a conflict in ``console= setup`` 19*7dbffd3fSCristian Souza --> initial console unavailable. E.g. some serial consoles are unreliable 20*7dbffd3fSCristian Souza due to serial IRQ issues (e.g. missing interrupt-based configuration). 219d85025bSMauro Carvalho Chehab Try using a different ``console= device`` or e.g. ``netconsole=``. 22*7dbffd3fSCristian Souza 23*7dbffd3fSCristian Souza4) **Binary exists but dependencies not available**: E.g. required library 24*7dbffd3fSCristian Souza dependencies of the init binary such as ``/lib/ld-linux.so.2`` missing or 25*7dbffd3fSCristian Souza broken. Use ``readelf -d <INIT>|grep NEEDED`` to find out which libraries 26*7dbffd3fSCristian Souza are required. 27*7dbffd3fSCristian Souza 28*7dbffd3fSCristian Souza5) **Binary cannot be loaded**: Make sure the binary's architecture matches 29*7dbffd3fSCristian Souza your hardware. E.g. i386 vs. x86_64 mismatch, or trying to load x86 on ARM 30*7dbffd3fSCristian Souza hardware. In case you tried loading a non-binary file here (shell script?), 31*7dbffd3fSCristian Souza you should make sure that the script specifies an interpreter in its 32*7dbffd3fSCristian Souza shebang header line (``#!/...``) that is fully working (including its 33*7dbffd3fSCristian Souza library dependencies). And before tackling scripts, better first test a 34*7dbffd3fSCristian Souza simple non-script binary such as ``/bin/sh`` and confirm its successful 35*7dbffd3fSCristian Souza execution. To find out more, add code ``to init/main.c`` to display 36*7dbffd3fSCristian Souza kernel_execve()s return values. 379d85025bSMauro Carvalho Chehab 389d85025bSMauro Carvalho ChehabPlease extend this explanation whenever you find new failure causes 399d85025bSMauro Carvalho Chehab(after all loading the init binary is a CRITICAL and hard transition step 40*7dbffd3fSCristian Souzawhich needs to be made as painless as possible), then submit a patch to LKML. 419d85025bSMauro Carvalho ChehabFurther TODOs: 429d85025bSMauro Carvalho Chehab 439d85025bSMauro Carvalho Chehab- Implement the various ``run_init_process()`` invocations via a struct array 449d85025bSMauro Carvalho Chehab which can then store the ``kernel_execve()`` result value and on failure 459d85025bSMauro Carvalho Chehab log it all by iterating over **all** results (very important usability fix). 46*7dbffd3fSCristian Souza- Try to make the implementation itself more helpful in general, e.g. by 47*7dbffd3fSCristian Souza providing additional error messages at affected places. 489d85025bSMauro Carvalho Chehab 49