If installed, cobbler will put an entry into all of your PXE menus allowing you to run memtest on physical systems without making changes in Cobbler. This can be handy for some simple diagnostics.
Steps to get memtest to show up in your PXE menus:
# yum install memtest86+ # cobbler image add --name=memtest86+ --file=/path/to/memtest86+ --image-type=direct # cobbler sync
memtest will appear at the bottom of your menus after all of the profiles.
However, if you already have a cobbler system record for the system, you can't get the menu. No problem!
cobbler image add --name=foo --file=/path/to/memtest86 --image-type=direct cobbler system edit --name=bar --mac=AA:BB:CC:DD:EE:FF --image=foo --netboot-enabled=1
The system will boot to memtest until you put it back to it's original profile.
When restoring the system back from memtest, make sure you turn it's netboot flag /off/ if you have it set to PXE first in the BIOS order, unless you want to reinstall the system!
cobbler system edit --name=bar --profile=old_profile_name --netboot-enabled=0
Naturally if you /do/ want to reinstall it after running memtest, just use --netboot-enabled=1
If you are curious about the image objects and what they do (and don't do) read AllAboutImages.