From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [PATCH] Make virtio devices multi-function Date: Tue, 22 Apr 2008 13:52:11 -0500 Message-ID: <480E33DB.7010108@codemonkey.ws> References: <1208873728-10194-1-git-send-email-aliguori@us.ibm.com> <480DF70D.8010609@qumranet.com> <480DFA3B.2000401@codemonkey.ws> <480DFB87.6090608@qumranet.com> <20080422153602.GA15542@dmt> <480E0FC0.4000401@codemonkey.ws> <480E11E2.3040706@qumranet.com> <480E12CF.9080108@codemonkey.ws> <20080422172645.GA16321@dmt> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel@lists.sourceforge.net, Chris Wright , Avi Kivity To: Marcelo Tosatti Return-path: In-Reply-To: <20080422172645.GA16321@dmt> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces@lists.sourceforge.net Errors-To: kvm-devel-bounces@lists.sourceforge.net List-Id: kvm.vger.kernel.org >>> For mass storage, we should follow the SCSI model with a single device >>> serving multiple disks, similar to what you suggest. Not sure if the >>> device should have a single queue or one queue per disk. >>> >> My latest thought it to do a virtio-based virtio controller. >> > > Why do you dislike multiple disks per virtio-blk controller? As > mentioned this seems a natural way forward. > Logically speaking, virtio is a bus. virtio supports all of the features of a bus (discover, hot add, hot remove). Right now, we map virtio devices directly onto the PCI bus. The problem we're trying to address is limitations of the PCI bus. We have a couple options: 1) add a virtio device that supports multiple disks. we need to reinvent hotplug within this device. 2) add a new PCI virtio transport that supports multiple virtio-blk devices within a single PCI slot 3) add a generic PCI virtio transport that supports multiple virtio devices within a single PCI slot 4) add a generic virtio "bridge" that supports multiple virtio devices within a single virtio device. #4 may seem strange, but it's no different from a PCI-to-PCI bridge. I like #4 the most, but #2 is probably the most practical. Regards, Anthony Liguori ------------------------------------------------------------------------- This SF.net email is sponsored by the 2008 JavaOne(SM) Conference Don't miss this year's exciting event. There's still time to save $100. Use priority code J8TL2D2. http://ad.doubleclick.net/clk;198757673;13503038;p?http://java.sun.com/javaone