From owner-freebsd-current@FreeBSD.ORG Tue May 27 07:45:27 2008 Return-Path: Delivered-To: current@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id D1B0F1065670 for ; Tue, 27 May 2008 07:45:27 +0000 (UTC) (envelope-from julian@elischer.org) Received: from outB.internet-mail-service.net (outb.internet-mail-service.net [216.240.47.225]) by mx1.freebsd.org (Postfix) with ESMTP id B632B8FC27 for ; Tue, 27 May 2008 07:45:27 +0000 (UTC) (envelope-from julian@elischer.org) Received: from idiom.com (mx0.idiom.com [216.240.32.160]) by out.internet-mail-service.net (Postfix) with ESMTP id 2B0592496; Tue, 27 May 2008 00:45:33 -0700 (PDT) Received: from julian-mac.elischer.org (localhost [127.0.0.1]) by idiom.com (Postfix) with ESMTP id B3D2E2D6022; Tue, 27 May 2008 00:45:26 -0700 (PDT) Message-ID: <483BBC1B.6040905@elischer.org> Date: Tue, 27 May 2008 00:45:31 -0700 From: Julian Elischer User-Agent: Thunderbird 2.0.0.14 (Macintosh/20080421) MIME-Version: 1.0 To: Poul-Henning Kamp References: <42521.1211829076@critter.freebsd.dk> In-Reply-To: <42521.1211829076@critter.freebsd.dk> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Ed Schouten , current@FreeBSD.org, arch@FreeBSD.org, Robert Watson , Ade Lovett , net@FreeBSD.org, "Bruce M. Simpson" Subject: Re: HEAD UP: non-MPSAFE network drivers to be disabled X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 27 May 2008 07:45:27 -0000 Poul-Henning Kamp wrote: > In message <20080526161608.GE64397@hoeg.nl>, Ed Schouten writes: > >> The new TTY layer should still support line disciplines, [...] > > Actually... I think it shouldn't. > > Line-disc's were introduced to interface weird-ass hardware like > digitizing tablets that had very high data rates, but very little > information (16 bit X, 16 bit Y and a couple of buttons, like modern > mice) which would cost inordinate amounts of CPU time to support > in userland on a VAX computer. > > If_slip.c happened in the kernel because there was no tun device, > people cranked the speed up all they could (Hands up: who has changed > the Xtal on a VAX serial port for faster SLIP ?) > > if_ppp happened because that was how if_slip did it. > > Today there is no longer a market for line disciplines and in > practice we have only one: the POSIX mandated "termios", which also > emulates the older "termio" ioctls. > > Anybody who cares to browse the three pages of text that RFC1055 > contains, will see that implementing SLIP in userland using tun(4) > and the code on the other three pages of RFC1055 is a trivial task > not even worthy of a SoC student. > > PPP over async is already much better handled in ppp(8) thanks > to Brians valiant effort back in the stoneage of the internet. > > We should summarily kill the concept of line disciplines as a > modular component and decide that TTYs can be used with termios(4) > or raw mode and leave it at that. > > Poul-Henning > However the line discipline was a very convenient place for netgraph to hook in without leaving the kernel. If you can supply an equally effective way to hook into a serial device in such a way that it appears to be a source/sink of bits then I don't care about line disciplins, but until you have a suggested replacement then leave them alone. There are MANY people using mpd with the netgraph ppp moduel hooked directly to the serial port via the netgraph line discipline.