Technical data

3. Base configuration
3.4. Hints To Identify Problems And Errors
fli4l logs all output produced while booting into the file (/var/tmp/boot.log). After the boot
process has finished you can review this file at the console or using the web interface.
Sometimes it is useful to generate a more detailed trace of the start sequence, e.g. to
analyze the boot process in case of problems. The variable DEBUG_STARTUP exists for this very
reason. Other settings help developers to find bugs in certain situations; these settings are also
documented in this section.
DEBUG_STARTUP Default Setting: DEBUG_STARTUP=’no’
If set to ‘yes’, each command to be executed is written to the console while booting. As a
change in syslinux.cfg is necessary for enabling this functionality, everything mentioned
for SER_CONSOLE also applies to this case. If you want to adapt syslinux.cfg by hand, you
need to insert fli4ldebug=yes to it. Nevertheless, DEBUG_STARTUP needs to be set to
‘yes’.
DEBUG_MODULES Default Setting: DEBUG_MODULES=’no’
Some modules are loaded automatically by the kernel without further notification. DEBUG_MODULES=’yes’
activates a mode showing the sequence of all modules being loaded, regardless whether
they are loaded explicitly by a script or automatically by the kernel.
DEBUG_ENABLE_CORE Default Setting: DEBUG_ENABLE_CORE=’no’
If this setting is activated, every program crash causes the creation of a so-called “core
dump”, a memory image of the process just before the crash. These files are saved
in the directory /var/log/dumps on the router and can be helpful in finding program
errors. More details details can be found in the section “Debugging programs on the
fli4l” (Page 244) in the documentation of the SRC package.
DEBUG_MDEV Default Setting: DEBUG_MDEV=’no’
With DEBUG_MDEV=’yes’ all actions related to the mdev daemon will be logged, in detail
all additions or removals of device nodes in /dev or the loading of firmware. Output is
directed to the file /var/log/mdev.log.
DEBUG_IPTABLES Default Setting: DEBUG_IPTABLES=’no’
With DEBUG_IPTABLES=’yes’ all iptables invocations are logged to /var/log/iptables.log,
including the return values.
DEBUG_IP Default Setting: DEBUG_IP=’no’
With DEBUG_IP=’yes’ all invocations of the program /sbin/ip are logged to the file
/var/log/wrapper.log.
3.5. Usage of a customized /etc/inittab
It is possible to let the “init” process start additional programs on additional consoles or to
change the default commands. An inittab entry is structured as follows:
device:runlevel:action:command
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