On Sun, Sep 22, 2019 at 08:03:56AM +0200, Heiko Schocher wrote: > +struct __attribute__ ((packed)) msg_queue_user { > + int type; /* CC1101_MSG_SET_ */ > +}; > + > +/* CC1101_MSG_DEFINE_CONFIG */ > +struct __attribute__ ((packed)) config_param { > + char addr; > + char val; > +}; {sigh} None of these structures are valid ones to be passing to/from userspace/kernel at all. Please fix them up to work properly (i.e. use the correct types and such). I think there's a "how to write a correct ioctl" document in the documentation directory somewhere, you might want to search for that. thanks, greg k-h