From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rusty Russell Subject: Re: Extending virtio_console to support multiple ports Date: Mon, 21 Sep 2009 14:50:45 +0930 Message-ID: <200909211450.47348.rusty@rustcorp.com.au> References: <20090826112718.GA11117@amit-x200.redhat.com> <20090831161925.GA22928@amit-x200.redhat.com> <4A9BFC31.9070005@codemonkey.ws> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: Anthony Liguori , Amit Shah , qemu-devel@nongnu.org, kvm@vger.kernel.org To: virtualization@lists.linux-foundation.org Return-path: Received: from ozlabs.org ([203.10.76.45]:33687 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753328AbZIUFUx (ORCPT ); Mon, 21 Sep 2009 01:20:53 -0400 In-Reply-To: <4A9BFC31.9070005@codemonkey.ws> Content-Disposition: inline Sender: kvm-owner@vger.kernel.org List-ID: On Tue, 1 Sep 2009 02:07:05 am Anthony Liguori wrote: > Amit Shah wrote: > Functionally speaking, both virtio-console and virtio-serial do the same > thing. In fact, virtio-console is just a subset of virtio-serial. > > If there are problems converging the two drivers in Linux, then I > suggest you have two separate driver modules in Linux. That would > obviously be rejected for Linux though because you cannot have two > drivers for the same device. Why should qemu have a different policy? I've been on leave, cheerfully not thinking about this. AFAICT, a console and serial are very similar, so it makes sense to merge them. But a serial port doesn't have framing either; if it does, it's something else. And generally using virtio framing in upper layers is a mistake (one we've made in the qemu implementations, but that's unfortunate). Thanks, Rusty. From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MpbKm-00023L-3m for qemu-devel@nongnu.org; Mon, 21 Sep 2009 01:21:08 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MpbKg-00022Q-U0 for qemu-devel@nongnu.org; Mon, 21 Sep 2009 01:21:07 -0400 Received: from [199.232.76.173] (port=34930 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MpbKg-000227-OG for qemu-devel@nongnu.org; Mon, 21 Sep 2009 01:21:02 -0400 Received: from ozlabs.org ([203.10.76.45]:45773) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1MpbKg-0004CF-7v for qemu-devel@nongnu.org; Mon, 21 Sep 2009 01:21:02 -0400 From: Rusty Russell Date: Mon, 21 Sep 2009 14:50:45 +0930 References: <20090826112718.GA11117@amit-x200.redhat.com> <20090831161925.GA22928@amit-x200.redhat.com> <4A9BFC31.9070005@codemonkey.ws> In-Reply-To: <4A9BFC31.9070005@codemonkey.ws> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200909211450.47348.rusty@rustcorp.com.au> Subject: [Qemu-devel] Re: Extending virtio_console to support multiple ports List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: virtualization@lists.linux-foundation.org Cc: Amit Shah , qemu-devel@nongnu.org, kvm@vger.kernel.org On Tue, 1 Sep 2009 02:07:05 am Anthony Liguori wrote: > Amit Shah wrote: > Functionally speaking, both virtio-console and virtio-serial do the same > thing. In fact, virtio-console is just a subset of virtio-serial. > > If there are problems converging the two drivers in Linux, then I > suggest you have two separate driver modules in Linux. That would > obviously be rejected for Linux though because you cannot have two > drivers for the same device. Why should qemu have a different policy? I've been on leave, cheerfully not thinking about this. AFAICT, a console and serial are very similar, so it makes sense to merge them. But a serial port doesn't have framing either; if it does, it's something else. And generally using virtio framing in upper layers is a mistake (one we've made in the qemu implementations, but that's unfortunate). Thanks, Rusty.