[seL4] Dynamic number of arguments in interface method

Hello Everyone, I'm trying to implement interface which will accept similar syntax like printf method in c is accepting. syntax of function in c: void printer(int i,char* format,...){ } However I have problem to create valid syntax in idl4 interface definition for CAmkES. Can somebody help me to create valid syntax for procedure definition used in interface? procedure Test { void printer(in int i,in string format,in ...); }; Or is this approach even supported? Also If there is more complex reference guide for idl4 used by CAmkES which I can use to find answers like this? Thank you for help and if question is stupid please accept my apologize I'm just starting to play with this project. BR, Casper