Embodiments of the invention relate to providing file system extended attribute support in an operating system. A request from an application to access extended attribute data in a multi-platform file system using an interface specified by the operating system is received. It is determined whether the specified interface supports an exchange of full content of the extended attribute data between the application and the multi-platform file system. Based on determining that the specified interface does not support an exchange of full content, the request is processed by an alternate interface. Based on the access being a read, the full content of the extended attribute data is retrieved and returned to the application using the alternate interface. Based on the access being a write, the full content of the extended attribute data is received from the application using the alternate interface and written to the multi-platform file system.