A vendor extension command is used to transport a proprietary message to a device (e.g., a solid state drive), to instruct the device to access and return data stored on the device (e.g., data that can be used for debugging). More specifically, a device that is coupled to a host system by a host bus interface (e.g., a Peripheral Component Interconnect Express bus) receives a command in a vendor extension of a standard driver (e.g., a Non-Volatile Memory Express driver). In response to the command in the vendor extension, data (e.g., debugging data) stored in memory on the device is accessed. The data can then be sent over the host bus interface to the host system. Thus, for example, a proprietary debugging framework can be used with a standards-based device.