Chapter 1 - How to get the MorphOS debug log
There are three different but complementary ways to get the MorphOS debug log:
1) Serial debug
The debug output is redirected to the RS232 serial port.
This is the preferred debug method because it only relies on the Quark
kernel availability. It works even when the rest of MorphOS is unusable
and it is the only way to debug hardcore problems.
There is no need to do anything special to enable it because it is the
built-in default debug output.
To capture debug information, you need a second computer, a nullmodem
cable and a serial terminal program. The output speed is 115200 bps and
serial settings are 8n1 (eight data bits, no parity, one stop bit).
The debug output is redirected to a memory buffer.
The buffer is managed by the Quark kernel and located outside the ABox's
memory space. It has a limited size (currently 4MB). When it fills up, it
will loop around and older entries will be overwritten by new ones.
Please note some firmware setups always clear memory during the warm boot
process. In this case, the RAM content is not preserved and the RamDebug
log is lost after a reboot.
To activate RamDebug, it is required to boot from the OpenFirmware using
the "ramdebug" argument.
boot boot.img ramdebug
To take a look at the debug log, it is first needed to manually extract it
using dedicated tools, such as:
- "GetRamDebugLog", a basic command line tool. It is able to save the
RamDebug buffer to a file. It's part of MorphOS 1.4.4 and up.
- "logTool", a GUI tool. More information at
The *exception* debug output is redirected in a console window.
The LogServer is always simultaneously used with Serial or RamDebug.
An exception happens when a program performs an invalid memory access or
executes an illegal processor instruction.
The LogServer is a dedicated "Log Task" task communicating with Exec's
exception-handler. Exec output is caught by the LogServer and redirected
in a console window.
Please note the LogServer doesn't display Alert() content and other
MorphOS debug messages.
Furthermore, its exception report is very limited and doesn't contain all
possible information. Worse, when the LogServer is running, usual RamDebug
and Serial logs are also modified and even cut down!
The LogServer is meant to be used complementary with RamDebug or Serial
debug... and by users only. Programmers should better not use it.
To activate the LogServer when booting MorphOS, use the "logserver"
argument from OpenFirmware. Exemple:
boot boot.img ramdebug logserver
You can ask for a bit more informative output:
boot boot.img ramdebug logserver edebugflags="logextended"
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