Messages in this thread Patch in this message | | | Date | Sun, 27 Dec 2009 16:03:29 +0100 | From | Andreas Mohr <> | Subject | [PATCH] Improve usability in case of init binary failure |
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On Tue, Nov 17, 2009 at 09:40:16PM +0100, Andreas Mohr wrote: > I'll submit a new version of this patch very soon.
Well, took quite a while longer, partly due to broken Broadcom USB host (OpenWrt fix to be submitted) and non-working USB-audio on nicer platforms.
Took most of the comments into account (thanks!), improved some wording.
Patch against current git, compile- and runtime-tested, checkpatch.pl'd (with a single nice hierarchy warning resulting from mixing git diff output and manual /dev/null diffing).
Thanks!
Signed-off-by: Andreas Mohr <andi@lisas.de>
diff --git a/init/main.c b/init/main.c index dac44a9..33748c6 100644 --- a/init/main.c +++ b/init/main.c @@ -836,7 +836,8 @@ 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 2009-12-27 16:25:29.521258205 +0100 +++ Documentation/init.txt 2009-12-27 15:47:46.000000000 +0100 @@ -0,0 +1,49 @@ +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) broken console device +D) binary exists but dependencies not available +E) binary cannot be loaded + +Detailed explanations: +0) Set "debug" kernel parameter (in bootloader config file or CONFIG_CMDLINE) + to get more detailed kernel messages. +A) 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, + to be pre-loaded by an 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. required 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. + In case you tried loading a non-binary file here (shell script?), + you should make sure that the script specifies an interpreter in its shebang + header line (#!/...) that is fully working (including its library + dependencies). And before tackling scripts, better first test a simple + non-script binary such as /bin/sh and confirm its successful execution. + To find out more, add code to init/main.c 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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