Re: ioctl number 0xF3

From: Petr Vandrovec (vandrove_at_vc.cvut.cz)
Date: 05/23/04

  • Next message: Roland McGrath: "[PATCH] bogus sigaltstack calls by rt_sigreturn" 
    Date:	Sun, 23 May 2004 03:35:37 +0200
To: Thomas Winischhofer <thomas@winischhofer.net>

    On Sat, May 22, 2004 at 05:37:57PM +0200, Thomas Winischhofer wrote:
    >
    > Hm. Were the matrox folks asked for a "clear interface" in advance when
    > they started using the 'n' ioctls? Am I too polite? ;)

    You are too polite.

    In the past ncpfs was using 'n' with 'all' subcodes assigned to it.
    Back when I needed some numbers, I simple shrunk ncpfs to 0x00-0xDF, assigning
    0xE0-0xFF to matroxfb (I maintain both, so it is simple...). It looks like that
    someone visited ncpfs's assignment since then, as now ncpfs has only 0x00-0x7F
    assigned to it (according to the ioctl-numbers; I have no idea who made this
    0x80-0xDF hole in my nice range).

    On other side, matroxfb uses standard VIDIOC_* v4l2 ioctls for exporting
    TV-out's brightness/saturation/... to the userspace. And it causes neverending
    pain. Currently Debian's /usr/include headers contain VIDIOC_S_CTRL
    definition:

    #define VIDIOC_S_CTRL _IOW ('V', 28, struct v4l2_control)

    while kernel uses

    #define VIDIOC_S_CTRL _IOWR ('V', 28, struct v4l2_control)

    and so no apps built with /usr/include headers on Debian do work on matroxfb's
    (or anyone else's) v4l2 interface :-( Better to not give description of your ioctls to anyone,
    or they'll "fix" them.
                                                    Best regards,
                                                            Petr Vandrovec
     
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

  • Next message: Roland McGrath: "[PATCH] bogus sigaltstack calls by rt_sigreturn"

    Relevant Pages