How do I troubleshoot startup?

jhsu · posted: 2011-09-08 15:55

I sometimes get a kernel panic during the startup process, and the only way out is to turn off the computer and start it up again.

The next time this happens, I'm booting up Puppy Linux from the other partition (dual boot setup) so I can look at the files in the hard drive (so as to avoid changing the critical files). Exactly where can I find all of the files logging the startup process?

dark-D · posted: 2011-09-08 17:41

the start-up logs are located in /var/log/boot
you have to be super user to see the content of the file.
in a terminal or in run type: gksu leafpad /var/log/boot

jhsu · posted: 2011-09-10 19:28

ICE-M wrote:the start-up logs are located in /var/log/boot
you have to be super user to see the content of the file.
in a terminal or in run type: gksu leafpad /var/log/boot

I'm in Puppy Linux right now (which i booted up immediately after getting the kernel panic), and I don't see any /var/log/boot file in the antiX Linux partition.

rokytnji · posted: 2011-09-11 06:59

jhsu wrote:
ICE-M wrote:the start-up logs are located in /var/log/boot
you have to be super user to see the content of the file.
in a terminal or in run type: gksu leafpad /var/log/boot
I'm in Puppy Linux right now (which i booted up immediately after getting the kernel panic), and I don't see any /var/log/boot file in the antiX Linux partition.

Fired up my IBM T23 to see. I dualboot Puppy 520 with AntiX . I figure a picture is worth a thousand words.
Boot file is showing right under rxvt and also showing in rxvt using ls command in /var/log in rox file manager in Puppy. So not understanding why you don't have or can see a /var/log/boot file even in Puppy.

Puppy 520 looking at AntiX /var/log/boot

jhsu · posted: 2011-09-17 01:17

I don't know why, but even a fresh installation of antiX Linux M11 doesn't provide a /var/log/boot file. Is there something I have to do to activate this?

rokytnji · posted: 2011-09-17 04:59

Between Kernel panics, Not finding a /var/log/boot file. I am starting to wonder.

Did you do a md5sum of downloaded iso before burning cd?

jhsu · posted: 2011-09-17 17:06

rokytnji wrote:Between Kernel panics, Not finding a /var/log/boot file. I am starting to wonder.

Did you do a md5sum of downloaded iso before burning cd?

The md5sum of the ISO file has the expected value. I used the ISO to install antiX Linux in VirtualBox (to take the CD and CD drive out of the equation), and I still don't see any /var/log/boot file.

oldhoghead · posted: 2011-09-17 17:29

jhsu,

look in /etc/default/.bootlogd, you should see:

# Run bootlogd at startup ?
BOOTLOGD_ENABLE=No

change the No to Yes

then reboot. and you will have a log file in /var

cheers,
ohh

jhsu · posted: 2011-09-17 17:52

oldhoghead wrote:jhsu,

look in /etc/default/.bootlogd, you should see:

# Run bootlogd at startup ?
BOOTLOGD_ENABLE=No

change the No to Yes

then reboot. and you will have a log file in /var

I just went to /etc/default/bootlogd, and the BOOTLOGD_ENABLE was already set to Yes.

I'm using the full 686 version of antiX Linux. Is /var/log/boot supposed to be enabled by default for all editions of antiX Linux (core, light/Fluxbox, and full/IceWM)? Is this supposed to work out-of-the-box, or is some tweaking supposed to be necessary?

oldhoghead · posted: 2011-09-17 18:33

antiX I think has had bootlogd enabled by default for some time now.

cheers,
ohh

chrishall57 · posted: 2011-09-17 21:12

I'm also getting the occassional kernel panic at boot.

/var/log/boot just says"nothing logged yet"

/etc/default/.bootlogd exists but is an empty file.

buttcoffee · posted: 2011-09-20 00:37

try after you enable it

update-rc.d bootlogd defaults

and if you wanna remove it

update-rc.d -f bootlogd remove

rustiguzzi · posted: 2011-10-19 09:01

I too would like to see a boot log, so I checked to see that BOOTLOGD_ENABLED=yes,
then ran update-rc.d as above and got this result:
-------------------------------------------------------------------------------------------------------------------------
root@antiX1:/etc/default# update-rc.d bootlogd defaults
update-rc.d: using dependency based boot sequencing
update-rc.d: warning: bootlogd start runlevel arguments (2 3 4 5) do not match
LSB Default-Start values (S)
update-rc.d: warning: bootlogd stop runlevel arguments (0 1 6) do not match
LSB Default-Stop values (none)
------------------------------------------------------------------------------------------------------------------------
Not being fluent in linux at this depth, I admit to being puzzled. Suggestions, anyone?

BitJam · posted: 2011-10-19 17:50

========= SCRAPER REMOVED AN EMBEDDED LINK HERE ===========
url was:"http://rhcelinuxguide.wordpress.com/2006/06/01/linux-kernel-panic-prevent-cardiac-arrest/"
linktext was:"This article"
====================================
gives some information on kernel panics and what to do about them. I suggest you scroll down to about halfway in the article where it says:

Code: Select all

So you’re trying to start Linux for the first time and … wham! You get messages like:

    Unable to mount root device.
    Kernel panic – not syncing.

In brief, the information printed on the screen during the panic will hold the best clues on how to fix the problem. If the kernel is unable to write to the root device then there won't be any clues at all on the hard drive. If there are clues left behind, they will most likely be in the dmesg log (/var/log/dmesg). If the panic was recorded then the message printed to the screen should show up in that log file and this will save you from having to copy the (useful part of the) message by hand.

Perhaps the best case scenario would be that you can copy the panic message from the dmesg log (or write down some meaningful information that is printed to the screen) and then Google for it and discover a boot parameter you can use to avoid the panic in the future.

BitJam · posted: 2011-10-19 18:09

A couple of more thoughts.

You can use the"vga=" boot parameter to increase the resolution of the screen so more of the panic message can stay on-screen.
========= SCRAPER REMOVED AN EMBEDDED LINK HERE ===========
url was:"http://www.pendrivelinux.com/vga-boot-modes-to-set-screen-resolution/"
linktext was:"this page"
====================================
contains a table of standard resolutions. You can also use"vga=ask" to get a list of modes available on your hardware. These boot parameters get typed in at the grub boot menu. Don't include the quote characters.

The panic is most likely due to your specific hardware combined with the version of the Linux kernel you are trying to boot. Googling for your computer model (or motherboard model) combined with"kernel panic" and/or the Linux kernel version may well get you to a solution without having to record the useful parts of the panic message displayed on the screen.