Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 28 Mar 2002 19:25:40 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 28 Mar 2002 19:25:31 -0500 Received: from nat-pool-rdu.redhat.com ([66.187.233.200]:900 "EHLO devserv.devel.redhat.com") by vger.kernel.org with ESMTP id ; Thu, 28 Mar 2002 19:25:18 -0500 Date: Thu, 28 Mar 2002 19:25:17 -0500 From: Pete Zaitcev Message-Id: <200203290025.g2T0PHr04174@devserv.devel.redhat.com> To: linux-kernel@vger.kernel.org Subject: Re: Char devices drivers In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org >> > Can anyone explain what is the utility of the callout devices >> > in the char drivers ??? The utility is this (mind, it is only a nice idea in someone's empty head, in reality it does not really work that way): 1. You run getty on /dev/cua0 or /dev/cua1. 2. Getty waits for the carrier, and keeps /dev/cuaN open. 3. Meanwhile, you can use cu, kermit, and uucico to dial out using /dev/ttya or /dev/ttyb. Sounds very nifty, and this is how SunOS worked and Solaris tries to (with devices renamed a bit). The devil is details, or course. The hellishly complicated semantics of this twin-tailed device makes the driver pretty buggy. >[...] > So eliminating cua means more work for the programmer but less confusion > for users. Overall, it's a good thing since there are many more users > than programmers. > > David Lawyer I think it's more important that devices work as advertised more often if drivers are simpler. In my expirience, users are not really confused by callout devices, but rather are annoyed when they step on a bug. -- Pete - 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/