Re: Problem with tcgetattr

From: Laurent H. (l.huge_at_nospam.wanadoo.fr)
Date: 09/06/03 

Date: Sat, 06 Sep 2003 11:27:07 +0200

Peter T. Breuer a écrit :

> That makes no difference. Which module registers the char device?
I'm not. I've only implemented a line discipline for the serial port,
but all the rest is the serial driver.
> That's the one whose ioctl functions are used.
>> $ strace stty < /dev/ttyS0
>> ...
>> ioctl(0, SNDCTL_TMR_TIMEBASE, 0xbffff7f0) = -1 EINVAL
>> (Invalid argument)
> There you are. You are intercepting the ioctl or else replacing the
> serial drivers ioctl. And not doing it right.
I've got not ioctl in my module, so what's doing it ?
>> ioctl (wrong flag !). Do I have to implement an ioctl inside my
>> module ?
> If you are the one regisitering the functions for that major/minor,
> yes, of course. Show us what cat /proc/devices shows. That'll tell
> us who has registered for the char device with major 4. Are you
> replacing the ioctl?
        $ cat /proc/devices
        Character devices:
          1 mem
          2 pty
          3 ttyp
          4 ttyS
          5 cua
          ...
        226 drm
        231 ccsds
        245 pcmcia
        Block devices:
        ...
The char device ccsds is a simple rw device in which I derivate the
CCSDS flow (spatial standard) ; it has nothing to do with serial
port, and I'm sure it doesn't interact with it.
So the only thing I do against serial module is the line discipline :
        struct tty_ldisc sport_ldisc = {
                magic : TTY_LDISC_MAGIC,
                name : "ccsds_sport_ldisc",
                flags : 0,
                open : sport_open,
                close : sport_close,
                receive_buf : sport_receive,
                receive_room : sport_room,
        };
which I register with tty_register_ldisc(N_TTY, &sport_ldisc) during
the module initialization.
Does that mean I replace the serial duty on ioctl ? 

-- 
Laurent H. (pour m'écrire, enlever nospam de l'adresse de réponse)

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