Obviously on (my) AmigaOne X5000 serial debug output is set as default.
Because: If I run LogTool and try to test debug output, nothing happens.

So, I have read the lines "What boot arguments are there?" in the FAQ, but frankly spoken this did not help me.

My question: What is the command line for booting MorphOS with Ram Debug output.

I tried:
'boot ide:0 boot.img rd'
response: 'boot - boot default, i.g., run 'bootcmd''

The only way I get MorphOS booting is:
'bootmorphos'

Any help is welcome.
Thanks!

Maybe you should give the boot arguments (rd) in this way:
MorphOS Boot Arguments on U-boot Systems

Hmmm, yes I already got this hint from roschmyr...thanks!

X5000>printenv morphosargs
## Error: "morphosargs" not defined

??

X5000> setenv morphosargs ramdebug
X5000> saveenv
SAving Environment to MMC...
Writing to MMC(0)... done

So, I will see if this has something changed...

Yes, the last one worked. Thanks Jochen! :)
Now I finally can send my bug report to Jacek... ;)