Messages in this thread Patch in this message | | | Date | Mon, 16 Nov 2009 20:40:15 +0100 | From | Andreas Mohr <> | Subject | [PATCH] FIX IT |
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ChangeLog: Partially fix B0RKEN kernel usability
checkpatch.pl'd, tested, applies cleanly to 2.6.32-rc7. Seemingly best to go via trusted mmotm.
Thanks as always,
Signed-off-by: Andreas Mohr <andi@lisas.de>
--- linux-2.6/init/main.c.orig 2009-11-16 20:13:08.000000000 +0100 +++ linux-2.6/init/main.c 2009-11-16 20:14:51.000000000 +0100 @@ -846,7 +846,8 @@ static noinline int init_post(void) run_init_process("/bin/init"); run_init_process("/bin/sh"); - panic("No init found. Try passing init= option to kernel."); + panic("No init found. Try passing init= option to kernel. " + "See Linux Documentation/init.txt for guidance."); } static int __init kernel_init(void * unused) --- /dev/null 2009-11-10 08:07:33.390012116 +0100 +++ linux-2.6/Documentation/init.txt 2009-11-16 20:17:57.000000000 +0100 @@ -0,0 +1,44 @@ +Explaining the dreaded "No init found." boot hang message +========================================================= + +OK, so you've got this pretty unintuitive message (currently located +in init/main.c) and are wondering what the H*** went wrong. +Some high-level reasons for failure (listed roughly in order of execution) +to load the init binary are: +A) Unable to mount root FS +B) init binary doesn't exist on rootfs +C) other requirements not met +D) binary exists but dependencies not available +E) binary cannot be loaded + +Detailed explanations: +0) Set "debug" kernel parameter (in bootloader or CONFIG_CMDLINE) +to get more detailed kernel messages. +A) Please 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 by +using initrd) +C) 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=. +D) e.g. crucial 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. +E) make sure the binary's architecture matches your hardware. +E.g. i386 vs. x86_64 mismatch, or trying to load x86 on ARM hardware. +Or did you try loading a non-binary file here!?! (shell script?) +To find out more, add code patch 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 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. + +Andreas Mohr <andi at lisas period de>
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