From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MYknK-0003mT-Ir for qemu-devel@nongnu.org; Wed, 05 Aug 2009 14:00:58 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MYknE-0003kd-FD for qemu-devel@nongnu.org; Wed, 05 Aug 2009 14:00:56 -0400 Received: from [199.232.76.173] (port=52852 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MYknE-0003ka-7x for qemu-devel@nongnu.org; Wed, 05 Aug 2009 14:00:52 -0400 Received: from mail2.shareable.org ([80.68.89.115]:56950) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1MYknD-0006h2-Lb for qemu-devel@nongnu.org; Wed, 05 Aug 2009 14:00:51 -0400 Date: Wed, 5 Aug 2009 19:00:49 +0100 From: Jamie Lokier Subject: Re: [Qemu-devel] Re: virtio-serial: An interface for host-guest communication Message-ID: <20090805180049.GC28738@shareable.org> References: <1248717876-17630-1-git-send-email-amit.shah@redhat.com> <4A6E0C9E.10908@codemonkey.ws> <20090727203214.GG15020@redhat.com> <20090727204627.GA32432@shareable.org> <4A6E3BDC.8050101@codemonkey.ws> <20090728103624.GA5176@amit-x200.redhat.com> <4A6F0048.1000103@codemonkey.ws> <20090729074418.GA24925@amit-x200.redhat.com> <20090729074827.GJ30449@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090729074827.GJ30449@redhat.com> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gleb Natapov Cc: kvm@vger.kernel.org, qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org, Amit Shah Gleb Natapov wrote: > On Wed, Jul 29, 2009 at 01:14:18PM +0530, Amit Shah wrote: > > But why do we want to limit the device to only one port? It's not too > > complex supporting additional ones. > > > > As I see it qemu and the kernel should provide the basic abstraction for > > the userspace to go do its job. Why create unnecessary barriers? > > > I agree. If userspace wants it may use only one channel and demultiplex > messages by itself, but we shouldn't force it to. Also one of the > requirements for virtio-serial is to have connect disconnect > notifications. It is not possible with demultiplexing in the userspace. I agree too, for all those reasons. However it would be useful if the devices provided a simpler way to be found by guest applications than /dev/vmch0, vmch1, vmch2... On Linux udev provides a sane way to find devices according to roles, subtypes, serial numbers, whatever you want, if the appropriate id codes are available from the devices and put into /sys/* by the kernel driver. That would make the devices much more useful to independent applications, imho. -- Jamie