From MorphOS website FAQ:
"Q: How do I setup or modify the auto-boot feature? (Open Firmware)
A: First make sure its working when typing the commands by performing a test boot.
Then, define a boot file and set options. Boot command and boot device will be added by using the Open Firmware.
> setenv boot-file boot.img ramdebug
There are alias names available if you did not remove them, so this /pci/ stuff can be replaced by a simple ide:0.
> setenv boot-device /pci/ide/disk@...
Now, we set the auto boot delay. By default the Open Firmware counts down from 5 before starting auto boot. This would be a 5 second delay. It is possible to set up lower or higher numbers. It is recommended to refrain from using values below 1000, because it may be very hard to re-enter the Open Firmware command line interface again otherwise. The optimal values are between 3000 and 10000. (4000 equals 4 seconds, 1000 equals 1 second, and so on.)
> setenv auto-boot-timeout 3000
You may skip this for now. Using "boot" command without any argument will use the configuration specified above. If its working fine you finally can enable automatic booting using those set-ups.
> setenv auto-boot? true
"
It works for me :-)
PZ.