| 1 | How to watch udev activity when booting
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| 2 | #######################################
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| 3 |
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| 4 |
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| 5 | 1) Make syslog start before udev:
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| 6 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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| 7 | Since udev writes all output to syslog, we need service syslog running before
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| 8 | udevd starts. There are two ways to achieve this.
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| 9 |
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| 10 | Either add the needed link to /etc/init.d/earlysyslog in /etc/init.d/boot.d/ manually. But it must start later then boot.rootfsck.
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| 11 |
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| 12 | Or you edit the service scripts itself and let insserv create the links. You
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| 13 | have to change earlysyslog and boot.udev:
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| 14 | /etc/init.d/earlysyslog
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| 15 | Add 'B' to 'Default-Start:' and 'boot.rootfsck' to 'Required-Start:'
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| 16 | # Required-Start: boot.rootfsck
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| 17 | # Default-Start: B 2 3 5
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| 18 | /etc/init.d/boot.udev
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| 19 | Add 'earlysyslog' to 'Required-Start'
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| 20 | # Required-Start: boot.rootfsck earlysyslog
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| 21 | Then call
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| 22 | /sbin/insserv -d earlysyslog
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| 23 | Check if earlysyslog comes before boot.udev in /etc/init.d/boot.d/S*
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| 24 |
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| 25 | You need /var on your root partition for that because boot.localfs is started
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| 26 | after udev. If you have a seperate /var partition, make it available somehow or
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| 27 | change the location of your syslog file.
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| 28 |
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| 29 |
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| 30 | 2) Enable logging
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| 31 | ^^^^^^^^^^^^^^^^^
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| 32 | set udev_log=info in /etc/udev/udev.conf.
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| 33 |
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| 34 | There is also debug, but you are very
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| 35 | probably not interested in the huge amount of debugging output from udev. It
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| 36 | writes about 70M logfile at a single boot.
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| 37 |
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| 38 | Many tools which are called from hotplug also respect the setting of udev_log.
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| 39 | But there might be some which need special actions to make them verbose.
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| 40 | [to be enhanced: list tools and their individual debug switches]
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| 41 |
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| 42 | You may change udevs loglevel at runtime with
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| 43 | udevcontrol log_priority=<level>
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| 44 |
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| 45 |
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| 46 | 3) Reboot
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| 47 | ^^^^^^^^^
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| 48 | For further processing of the logging output you should get a clean logfile at
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| 49 | next boot. Just move the old logfile away. Syslog will still use the moved file
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| 50 | until shutdown (until syslog restarted).
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| 51 | mv /var/log/messages /var/log/messages.`date +%s`
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| 52 |
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| 53 | Then reboot.
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| 54 |
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| 55 |
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| 56 | 4) Getting logged events sorted
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| 57 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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| 58 | There is a script 'show_event_log' which may be used to extract info out of
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| 59 | /var/log/messages. Call it
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| 60 | show_event_log <first> [<last> [<list of event types>] ]
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| 61 | <first> is the sequence number of the first event you are interested in.
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| 62 | <last> is the number of the last event. You may write 'last' literally. It may
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| 63 | also be omitted if you want to see a single event.
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| 64 | <list> is a list of event types you like to see. If you omit it, you get most
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| 65 | events, not all. Some are exclude by default. Use " " as list if you
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| 66 | want to see really all. Or edit the list of skipped events in the first
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| 67 | lines of the script
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| 68 | If you don't use /var/log/messages as lockfile you may set the environment
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| 69 | variable MESSAGES=<logfile>.
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| 70 |
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| 71 | The script is slowly. It is just a quick hack. The larger the syslog file the
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| 72 | slower the script. Therefore always boot with a fresh logfile.
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| 73 | Improvements are welcome.
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| 74 |
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| 75 |
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| 76 | Have a lot of fun, as always ;)
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| 77 |
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