It's layout is simple:

• one line starting with the word "LABEL" defines the name of the configuration that will follow,
• then a line with "EXEC Kickstart/loader" that you will probably never change
  (it is the program that relocates the modules in memory before they are executed),
• then lines that start with the word "MODULE" which allow you to declare each module that should be loaded by this configuration,
• lines beginning with a semi-colon are simply comments (and there's plenty of them)
• blank or empty lines are significant and denote the end of one configuration and the start of another, which means that you must be careful not leave any empty lines unless you are defining multiple configurations.

; Configuration name LABEL Default ; Exec name EXEC Kickstart/loader ; ; PPC native modules ; MODULE Kickstart/kernel MODULE Kickstart/FastFileSystem ....etc.

In order to create several configurations, you just have to edit the Kicklayout file. As an example, you can create one default configuration that will be automatically loaded at each system boot, a backup configuration you will be able to always boot, and another one to test a module you just modified (if you are a developer), etc, for example:

; Configuration name LABEL Default ; Exec name EXEC Kickstart/loader ; ; PPC native modules ; MODULE Kickstart/kernel MODULE Kickstart/FastFileSystem ....etc. ; Configuration name LABEL Testing ; Exec name EXEC Kickstart/loader ; ; PPC native modules ; MODULE Kickstart/updated-kernel MODULE Kickstart/FastFileSystem ....etc.

You can set the configuration you want to boot by going into the U-Boot Boot Selection menu and modifying the "Configuration" field to the name of the configuration you want, in this case "Testing". If you don't do this, and let the machine boot automatically, the configuration called "Default" in the Kicklayout file will be loaded.

Alternatively, all configurations in the Kicklayout file will appear in the SLB Menu and you can dynamically select it from there during the boot process. On the other hand, if you modified the "Configuration" field as discussed above, this configuration will be pre-selected in the SLB Menu, but you can easily select one of the other configurations instead, so it can be very flexible.

One word of Warning! If you use a customised Kicklayout file, be sure to save it somewhere else when performing upgrades of the AmigaOS otherwise it could be deleted or overwritten.