Need to write a driver supports reading the file in ASCII format and write messages to it via a custom process: ioctl_set_msg(file_desc, msg). Supports removal of posts: ioctl_msg_delete.
Don't tell me how to open the file in the address space of the kernel and read/record messages in it, and send the ioctl? Here is an example www.crossplatform.ru/?q=node/342
but it all happens directly with the device instead of through the file.