Critical workload check

The application relates to a method of initialising rendering at a graphics processing unit configured to perform safety-critical rendering within a graphics processing system. The method comprises: generating configuration data for initialising rendering of safety critical graphical data at the graphics processing unit then receiving the configuration data for initialising rendering at the graphics processing unit. The graphics processing unit is then configured in accordance with the configuration data for initialising rendering and it is determined whether the graphics processing unit is correctly configured in accordance with the configuration data and if so, proceeding with the rendering of the safety-critical graphic data. A safety controller external to the graphics processing unit determines, possibly by the expiration of a timer, if an initialisation error has occurred in response to determining that the graphics processing unit is not correctly configured in accordance with the configuration data and if such an error has occurred the safety controller may cause the processing unit to be reset. The safety controller may generate the configuration data by writing one or more register entries into one or more registers or the firmware of the graphics processing unit my generate said data. The configuration checking process may involve reading back the configuration data from one or more registers and comparing the read back entries with the expected entries specified by the configuration data wherein the comparison may involve comparing checksums of the respective datasets.