Re: [PATCH 4/6] drivers:misc: sources for Init manager module

From: Pavan Savoy
Date: Wed Mar 24 2010 - 12:35:26 EST


--- On Wed, 24/3/10, Greg KH <gregkh@xxxxxxx> wrote:

> From: Greg KH <gregkh@xxxxxxx>
> Subject: Re: [PATCH 4/6] drivers:misc: sources for Init manager module
> To: "Marcel Holtmann" <marcel@xxxxxxxxxxxx>
> Cc: "Pavan Savoy" <pavan_savoy@xxxxxxxxxxx>, "PavanSavoy" <pavan_savoy@xxxxxx>, "alan@xxxxxxxxxxxxxxxxxxx" <alan@xxxxxxxxxxxxxxxxxxx>, "linux-kernel@xxxxxxxxxxxxxxx" <linux-kernel@xxxxxxxxxxxxxxx>
> Date: Wednesday, 24 March, 2010, 9:56 PM
> On Wed, Mar 24, 2010 at 09:11:45AM
> -0700, Marcel Holtmann wrote:
> > > I wanted to somehow put this in staging because
> then it would probably have a thorough architectural review
> process.
> > > Some details about this driver -
> > >
> > > 1. This driver will be used by
> Bluetooth-BlueZ/FM-V4L2 and GPS (probably character device
> driver) using the EXPORTED symbols (-register/_unregister).
> > >
> > > 2. Much like the hciattach daemon which maintains
> N_HCI bluetooth line discipline, this driver will also have
> a User-Space  N_TI_WL Init manager (UIM) maintaining
> the Line discipline.
> >
> > can you explain why you think this is needed and we
> can not interface
> > this directly. If it is a serial port, what protocol
> does it talk?
> >
> > > 3. Because of the UIM should know when to
> install/uninstall line discipline, the /sys entry is created
> a root called UIM (a new kobject) and UIM daemon would write
> it's PID to it.
> >
> > I don't understand this. This sounds like a broken
> concept to me.
>
> I also agree, those sysfs files are not acceptable, and
> will not work
> as-designed due to the pid namespace issues :(

Ok, How do I then from kernel space, ask a user-space daemon to open the TTY port and do a tiocsetd on it ?
[i.e ask for a line discipline to be installed ?]

Can't open the TTY and TIOCSETD upon boot, because BT, FM and GPS might be used or not used anytime.

And the idea of creating a device node, specifically for this and then doing an fasync/SIGIO was somehow rubbished.

>
> thanks,
>
> greg k-h
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