From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH] Inter-VM shared memory PCI device Date: Thu, 11 Mar 2010 15:07:57 +0200 Message-ID: <4B98EB2D.4010606@redhat.com> References: <1267833161-25267-1-git-send-email-cam@cs.ualberta.ca> <201003101504.22110.arnd@arndb.de> <4B9892B7.7030605@redhat.com> <201003111357.53025.arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Cam Macdonell , qemu-devel@nongnu.org, kvm@vger.kernel.org To: Arnd Bergmann Return-path: Received: from mx1.redhat.com ([209.132.183.28]:58642 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752268Ab0CKNIP (ORCPT ); Thu, 11 Mar 2010 08:08:15 -0500 In-Reply-To: <201003111357.53025.arnd@arndb.de> Sender: kvm-owner@vger.kernel.org List-ID: On 03/11/2010 02:57 PM, Arnd Bergmann wrote: > On Thursday 11 March 2010, Avi Kivity wrote: > >>> A totally different option that avoids this whole problem would >>> be to separate the signalling from the shared memory, making the >>> PCI shared memory device a trivial device with a single memory BAR, >>> and using something a higher-level concept like a virtio based >>> serial line for the actual signalling. >>> >>> >> That would be much slower. The current scheme allows for an >> ioeventfd/irqfd short circuit which allows one guest to interrupt >> another without involving their qemus at all. >> > Yes, the serial line approach would be much slower, but my point > was that we can do signaling over "something else", which could > well be something building on irqfd. > Well, we could, but it seems to make things more complicated? A card with shared memory, and another card with an interrupt interconnect? -- error compiling committee.c: too many arguments to function