Lets get organized ;) :
My objective:
=============
I'm planing to port FreeBSD's snp device to Linux (http://www.freebsd.org/cgi/cvsweb.cgi/src/sys/dev/snp/snp.c). It snoops a tty (http://www.svbug.com/cgi-bin/man.cgi?comd=8+watch)
My Questions: ============= 1. The only information I was able to find regarding tty layer is:
http://www.linuxdevices.com/articles/AT3711365653.html
It only explains how to code a tty driver, but it says nothing about tty layer design and structure.
Is there any further information aviable?
2. After reading FreeBSD snp driver sources (see link above) I realised It works by replacing target tty-device line discipline with its own one.
Ive been reading through "drivers/char/tty_io.c" and "drivers/char/n_tty.c" but I just cant understand how the tty driver and line disciplines are supposed to work together. Of course, I'm missing the concept of line discipline.
Can someone please how does a line discipline work?
Wouldnt that approach (replacing the line discipline) work only with certain tty devices?
3. Even If I manage to code a line discipline doing what I want.....
The max number of line disciplines (NR_LDISCS (tty.h)) and the number assigned to each one (N_TTY ... (termios.h)) is hardcoded.
How could I register the discipline without having to patch the kernel? Is there any known trick for doing that?
Thanks in Advance:
Alfonso Acosta
-- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
