From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753431Ab0CXRF1 (ORCPT ); Wed, 24 Mar 2010 13:05:27 -0400 Received: from web94909.mail.in2.yahoo.com ([203.104.17.168]:30903 "HELO web94909.mail.in2.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751795Ab0CXRF0 convert rfc822-to-8bit (ORCPT ); Wed, 24 Mar 2010 13:05:26 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.co.in; h=Message-ID:X-YMail-OSG:Received:X-Mailer:Date:From:Subject:To:Cc:In-Reply-To:MIME-Version:Content-Type:Content-Transfer-Encoding; b=r+r+OX9JnICkt9LOffv6jTZ0FPmAWNiWk3pS9qx20s3+2A315rmlErBdk2jEzRS6uqrDetuNb7n5j3546e88Ri1lZN7gYnaoMq/ICf0kmkYaejrhT58aNo1LWgnyS7AjUvy/In23Q15Z+C+jR9sUU/v5T6wOBR4GsHdabtQWVH8=; Message-ID: <802911.82166.qm@web94909.mail.in2.yahoo.com> X-YMail-OSG: 63KeZEUVM1kyzWoUKTghfEHcl3n9iXfZIw7uQPdf3fXsM.b g7QXGcNw_WsX4UHVFzW1NgEbRf_mUVqP..z4lRztaOXIuzc7pIULLsHJiDy4 A.Jjw4xnJ_wip8mlDVQ7fc09.Nikv9HvBQsN1M6wH_jaBznjWHRmtmrJ5bk3 pHoIsyjIKKcJ6P5G5aNe8TCMjaJiCVO67P6s82xBTbpC1vIHR.RFQELUYwue pyM7aSp7xKyUGvmY4VlaWtObI0vCaUSdF7q0vuOTpVy9SIFyyiyjOwaCkxnF RWhAO9rZBw13TkxO11Pqsr9s- X-Mailer: YahooMailClassic/10.0.8 YahooMailWebService/0.8.100.260964 Date: Wed, 24 Mar 2010 22:35:23 +0530 (IST) From: Pavan Savoy Subject: Re: [PATCH 4/6] drivers:misc: sources for Init manager module To: Greg KH Cc: Marcel Holtmann , PavanSavoy , "alan@lxorguk.ukuu.org.uk" , "linux-kernel@vger.kernel.org" In-Reply-To: <20100324165222.GA9922@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --- On Wed, 24/3/10, Greg KH wrote: > From: Greg KH > Subject: Re: [PATCH 4/6] drivers:misc: sources for Init manager module > To: "Pavan Savoy" > Cc: "Marcel Holtmann" , "PavanSavoy" , "alan@lxorguk.ukuu.org.uk" , "linux-kernel@vger.kernel.org" > Date: Wednesday, 24 March, 2010, 10:22 PM > On Wed, Mar 24, 2010 at 10:05:19PM > +0530, Pavan Savoy wrote: > > --- On Wed, 24/3/10, Greg KH > wrote: > > > > > From: Greg KH > > > Subject: Re: [PATCH 4/6] drivers:misc: sources > for Init manager module > > > To: "Marcel Holtmann" > > > Cc: "Pavan Savoy" , > "PavanSavoy" , > "alan@lxorguk.ukuu.org.uk" > , > "linux-kernel@vger.kernel.org" > > > > 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 ?] > > What would cause the kernel to want to tell userspace to do > this?  Is it > an external event that happens somehow that userspace > should know to > look for? Yes, Userspace events like opening the /dev/radio0 device for FM, or hci0 interface for BT. However the apps/stack would not want to know what LDISC is being used underneath, well they might not even want to know whether it's TTY or USB/i2C - right ? > > Can't open the TTY and TIOCSETD upon boot, because BT, > FM and GPS > > might be used or not used anytime. > > What causes them to want to be used?  The user, > right? > > > And the idea of creating a device node, specifically > for this and then > > doing an fasync/SIGIO was somehow rubbished. > > Why? It does pretty much the same thing, But we would be stuffing in more interfaces to the already huge driver. I mean just 3 fops on the device ? open/ioctl-fasync/close - but it also uses the SIGnaling concept - but not via PID though. Alan's talking about opening up the LDISC installation to kernel (say EXPORTING tty_set_ldisc/tiocsetd), That's like ideal scenario in this case. > > thanks, > > greg k-h > The INTERNET now has a personality. YOURS! See your Yahoo! Homepage. http://in.yahoo.com/