linux - Kernel logs and Boot logs

07
2014-04
  • Vigneshwaren

    I am trying to analyse the logs of whats happening during boot.

    Grub config

    My GRUB_CMDLINE_LINUX_DEFAULT option in /etc/default/grub reads

    GRUB_CMDLINE_LINUX_DEFAULT=

    dmesg

    I have analyzed my dmesg dump. I am unsure where this is a complete account of what happens when my system boots. Also there are jumps in the log file. I find logs of events around 7secs into boot and suddenly it jumps to 21secs into boot.

    initrd

    When I choose the kernel to boot, the following messages are shown..

    Loading vmliunx-3.12.4...
Loading initial ramdisk...

    and the system stalls for ~20secs and then the init scripts that are started are printed. I would like to know how I can log what's happening during this 'stall'. I know it is impossible to actually log the initrd operations. But what happens after that? Is there a set of tools that I can use/enable to log and analyse what's happening here. I have tried bootlogd, but to no avail.

    And, I have a Ubuntu 12.10. Thanks in advance

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    Related Question

    Discover linux kernel boot options
  • tzot

    Is there a cross-distribution way to know the boot parameters supplied to the kernel?


    • Related Answers
  • quack quixote

    Assuming you're asking about the options passed to the current-running kernel?

    1. If the /proc filesystem is in use, /proc/cmdline tells you exactly what options were passed to the kernel.

      $ cat /proc/cmdline  
root=UUID=3630dd43-f9f9-40b1-8a5f-72c13f2b309c ro quiet splash

    2. If there's no /proc filesystem, you can get an idea by finding the current kernel's entry in grub.conf or other bootloader configuration. (Use "uname -r" to see what kernel is currently running.) This won't tell you what WAS used to boot the current kernel, just what is NORMALLY used.

  • Ryan

    I'm guessing you're talking about the Linux Kernel, so there is a set of standard parameters which it accepts.