Creating a new Swi with the XGCONF configuration tool is shown here. The Swi module itself can be configured to specify the number of Swi priority levels that are being used by the system. Constraining this value to less than the maximum is a memory optimization, since the Swi stack will need to grow every time one Swi can be preempted by another one of higher priority. Setting this value as low as possible will minimize the size of the stack allocation that is required. The Swi instance itself will be configured with the name of the function to be run, any static constant values that should be passed as an argument to the function, as well as the Swi’s priority and initial trigger value.