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    SubjectRe: [PATCH 4/6] drivers:misc: sources for Init manager module
    --- On Wed, 24/3/10, Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:

    > From: Alan Cox <alan@lxorguk.ukuu.org.uk>
    > Subject: Re: [PATCH 4/6] drivers:misc: sources for Init manager module
    > To: "Pavan Savoy" <pavan_savoy@yahoo.co.in>
    > Cc: "Marcel Holtmann" <marcel@holtmann.org>, "Greg KH" <gregkh@suse.de>, "PavanSavoy" <pavan_savoy@ti.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
    > Date: Wednesday, 24 March, 2010, 10:56 PM
    > > Isn't there a mechanism for the
    > tty_set_ldisc to do what _open does ?
    > > I mean there might be plenty of devices on UART which
    > might not need /dev/tty at all ? i.e An App need not open
    > for a ldisc to be installed.
    >
    > There is no mechanism to have an open tty without having an
    > open file
    > attached to it - and changing that would be very very non
    > trivial. Plus
    > you still need a way to tell the kernel you want the device
    > in question
    > active. That probably should get addressed some day but its
    > not a quick
    > fix up!

    Which puts me back to square 1, the requirement is TTY device should be open, only when either BT, FM or GPS would want to use it.
    [with your patch one of the steps of installing ldisc would be reduced upon opening].

    Now from kernel-space which is the first to get notification about requirement of BT/FM or GPS, I somehow have to communicate it to user-space, without the much disliked sysfs entry method.

    How do I tell the user-space when I want the TTY device to be opened ?
    Actually why do I even need a TTY device in this case - right ?
    ldisc driver can do the tty->ops->write and tty_read and put it up on different interfaces like eth0/hci0 or /dev/radio0 etc..

    That would mean, a device can be on UART, a ldisc driver attached to it, and doesn't require a user-space daemon to maintain the device node.

    >
    > Alan
    >


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