From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1LWExp-0002og-TI for qemu-devel@nongnu.org; Sun, 08 Feb 2009 14:05:09 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1LWExo-0002lS-1R for qemu-devel@nongnu.org; Sun, 08 Feb 2009 14:05:09 -0500 Received: from [199.232.76.173] (port=40387 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1LWExn-0002kp-Tm for qemu-devel@nongnu.org; Sun, 08 Feb 2009 14:05:07 -0500 Received: from e36.co.us.ibm.com ([32.97.110.154]:58176) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1LWExl-0005bh-Gl for qemu-devel@nongnu.org; Sun, 08 Feb 2009 14:05:05 -0500 Received: from d03relay02.boulder.ibm.com (d03relay02.boulder.ibm.com [9.17.195.227]) by e36.co.us.ibm.com (8.13.1/8.13.1) with ESMTP id n18J3wF2023051 for ; Sun, 8 Feb 2009 12:03:58 -0700 Received: from d03av01.boulder.ibm.com (d03av01.boulder.ibm.com [9.17.195.167]) by d03relay02.boulder.ibm.com (8.13.8/8.13.8/NCO v9.1) with ESMTP id n18J52tq207610 for ; Sun, 8 Feb 2009 12:05:02 -0700 Received: from d03av01.boulder.ibm.com (loopback [127.0.0.1]) by d03av01.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id n18J51dX010818 for ; Sun, 8 Feb 2009 12:05:01 -0700 Message-ID: <498F2CC8.6090607@us.ibm.com> Date: Sun, 08 Feb 2009 13:04:40 -0600 From: Anthony Liguori MIME-Version: 1.0 References: <1233826439-16856-1-git-send-email-avi@redhat.com> <498B5962.2010202@us.ibm.com> <498BFA4D.6010107@redhat.com> <498C5377.1000202@us.ibm.com> <498DFA41.3010202@redhat.com> <498E1E45.3000307@us.ibm.com> <498EA648.4030502@redhat.com> <498F1D6E.3070106@us.ibm.com> <498F1EA1.8060803@redhat.com> In-Reply-To: <498F1EA1.8060803@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: [Qemu-devel] Re: [PATCH 0/4] Block DMA helpers (v2) Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Avi Kivity Cc: qemu-devel@nongnu.org Avi Kivity wrote: > We could replace > > struct iovec in_sg[VIRTQUEUE_MAX_SIZE]; > struct iovec out_sg[VIRTQUEUE_MAX_SIZE]; > > by QEMUSGList, which would be a minor improvement, but I thought > things were very different for some reason. I'm not sure that it's just a minor improvement. To maintain this interface, we have to map the full request. If we exposed QEMUSGLists, then each device could choose the mapping policy. Since there's no good reason to use virtio to DMA MMIO memory, I'm unsure which is the best approach. > An example would be how the code is structured now (as opposed to how > I thought it was structured). Okay, I was certain I was missing something obvious :-) Regards, Anthony Liguori