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” 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 /dev/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.