On Wed, Feb 03, 2021 at 06:53:56PM +0300, Sergei Shtepa wrote: > --- a/include/uapi/linux/dm-ioctl.h > +++ b/include/uapi/linux/dm-ioctl.h > @@ -214,6 +214,15 @@ struct dm_target_msg { > char message[0]; > }; > > +enum { > + REMAP_START_CMD = 1, > + REMAP_FINISH_CMD, Don't you need to say what REMAP_FINISH_CMD is explicitly? > +}; > + > +struct dm_remap_param { > + uint8_t cmd; > + uint8_t params[0]; These need to be __u8, "uint8_t" is not a valid type that crosses the user/kernel boundry. thanks, greg k-h