From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758594AbZIQNGY (ORCPT ); Thu, 17 Sep 2009 09:06:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758464AbZIQNGX (ORCPT ); Thu, 17 Sep 2009 09:06:23 -0400 Received: from mx1.redhat.com ([209.132.183.28]:28013 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758405AbZIQNGW (ORCPT ); Thu, 17 Sep 2009 09:06:22 -0400 To: Anthony Liguori Cc: Alan Cox , Amit Shah , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: Re: [PATCH] virtio_console: Add support for multiple ports for generic guest and host communication References: <1252678386-17404-1-git-send-email-amit.shah@redhat.com> <1252678386-17404-2-git-send-email-amit.shah@redhat.com> <20090911170010.34c80f2d@linux.intel.com> <20090911163806.GB25535@amit-x200.redhat.com> <4AAA8838.1080106@codemonkey.ws> <20090911173307.GB27046@amit-x200.redhat.com> <4AAA8A56.3040707@codemonkey.ws> <20090916112332.6bf981a5@linux.intel.com> <4AB164A0.8000402@codemonkey.ws> From: Markus Armbruster Date: Thu, 17 Sep 2009 15:06:20 +0200 In-Reply-To: <4AB164A0.8000402@codemonkey.ws> (Anthony Liguori's message of "Wed\, 16 Sep 2009 17\:20\:16 -0500") Message-ID: <87tyz1en5f.fsf@pike.pond.sub.org> User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Anthony Liguori writes: > Alan Cox wrote: >>> This device is very much a serial port. I don't see any reason not >>> to treat it like one. >>> >> >> Here are a few >> >> - You don't need POSIX multi-open semantics, hangup and the like >> > > We do actually want hangup and a few other of the tty specific ops. The > only thing we really don't want is a baud rate. And a line discipline, and messing with the controlling terminal, and group/session ID, and window size, and software flow control, ... >> - Seek makes sense on some kinds of fixed attributes >> > > I don't think we're dealing with fixed attributes. These are streams. > Fundamentally, this is a paravirtual uart. The improvement over a > standard uart is that there can be a larger number of ports, ports can > have some identification associated with them, and we are not > constrained to the emulated hardware interface which doesn't exist on > certain platforms (like s390). [...] Well, really fundamentally, this is just a reliable full-duplex byte stream, with connect and hangup notification. To me, that sounds more like TCP with an address family almost, but not quite AF_UNIX, but that case was thrown out of court long ago, so here we are.