On 11/15/20 11:21 AM, Maximilian Luz wrote: > +#define SSAM_CDEV_REQUEST _IOWR(0xA5, 1, struct ssam_cdev_request) All ioctl major numbers (0xA5) should be documented in Documentation/userspace-api/ioctl/ioctl-number.rst Apologies if I missed it somewhere else. thanks. -- ~Randy