From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161123AbVIPIHJ (ORCPT ); Fri, 16 Sep 2005 04:07:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161124AbVIPIHJ (ORCPT ); Fri, 16 Sep 2005 04:07:09 -0400 Received: from mtagate4.de.ibm.com ([195.212.29.153]:13020 "EHLO mtagate4.de.ibm.com") by vger.kernel.org with ESMTP id S1161123AbVIPIHG (ORCPT ); Fri, 16 Sep 2005 04:07:06 -0400 Subject: Re: [patch 2/7] s390: 3270 fullscreen view. From: Martin Schwidefsky Reply-To: schwidefsky@de.ibm.com To: Greg KH Cc: Christoph Hellwig , akpm@osdl.org, rbh00@utsglobal.com, linux-kernel@vger.kernel.org In-Reply-To: <20050915172432.GA9980@kroah.com> References: <20050914155345.GA11478@skybase.boeblingen.de.ibm.com> <20050914161022.GA4230@infradead.org> <1126719107.4908.29.camel@localhost.localdomain> <20050915172432.GA9980@kroah.com> Content-Type: text/plain Date: Fri, 16 Sep 2005 10:07:08 +0200 Message-Id: <1126858028.4923.11.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2005-09-15 at 10:24 -0700, Greg KH wrote: > On Wed, Sep 14, 2005 at 07:31:46PM +0200, Martin Schwidefsky wrote: > > +struct class *class3270; > > Isn't this a tty driver already? If so, you don't need to create your > own class, your devices will just show up in the /sys/class/tty/ area > just fine. > > Or am I missing something here? I don't think we can use the tty class for the 3270 driver. The reason is that there are several ways to access the 3270 device. One of them is the tty view. Another is the fullscreen view that has nothing to do with ttys. It allows an application to create its own 3270 data stream without the line discipline of the tty interfering. 3270 devices are strange beasts when you compare them to you standard terminal. You don't get an interrupt for every character you type, but only if special keys are pressed. One of them is . The current implementation of the tty view has an input line at the end of the 3270 screen and we get complete lines as input. That halfway works for normal command input although tab completion doesn't work. It completly breaks for editors, e.g. if you try to use vi on a 3270 tty you are in for nasty surprises. The only way to get an editor working on the 3270 is the fullscreen view where the editor itself can setup the complete screen. If you ever used an editor on an classic s390 operating system you know what I'm talking about. To cut the long story short, there is more to a 3270 device then the tty view. In fact you can compile the 3270 driver without the tty view and only with the fullscreen view. We still should have a class for the devices, do we not ? -- blue skies, Martin Martin Schwidefsky Linux for zSeries Development & Services IBM Deutschland Entwicklung GmbH