From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Npi7c-0000yp-Bj for qemu-devel@nongnu.org; Thu, 11 Mar 2010 08:08:16 -0500 Received: from [199.232.76.173] (port=54649 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Npi7b-0000yY-UO for qemu-devel@nongnu.org; Thu, 11 Mar 2010 08:08:15 -0500 Received: from Debian-exim by monty-python.gnu.org with spam-scanned (Exim 4.60) (envelope-from ) id 1Npi7b-0006nH-C7 for qemu-devel@nongnu.org; Thu, 11 Mar 2010 08:08:15 -0500 Received: from mx1.redhat.com ([209.132.183.28]:56443) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1Npi7a-0006n9-PT for qemu-devel@nongnu.org; Thu, 11 Mar 2010 08:08:15 -0500 Message-ID: <4B98EB2D.4010606@redhat.com> Date: Thu, 11 Mar 2010 15:07:57 +0200 From: Avi Kivity MIME-Version: 1.0 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> In-Reply-To: <201003111357.53025.arnd@arndb.de> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] Re: [PATCH] Inter-VM shared memory PCI device List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Arnd Bergmann Cc: Cam Macdonell , qemu-devel@nongnu.org, kvm@vger.kernel.org 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