From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: Re: [PATCH] Make virtio devices multi-function Date: Tue, 22 Apr 2008 12:36:02 -0300 Message-ID: <20080422153602.GA15542@dmt> References: <1208873728-10194-1-git-send-email-aliguori@us.ibm.com> <480DF70D.8010609@qumranet.com> <480DFA3B.2000401@codemonkey.ws> <480DFB87.6090608@qumranet.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel@lists.sourceforge.net, Chris Wright To: Avi Kivity Return-path: Content-Disposition: inline In-Reply-To: <480DFB87.6090608@qumranet.com> 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 On Tue, Apr 22, 2008 at 05:51:51PM +0300, Avi Kivity wrote: > Anthony Liguori wrote: > > Avi Kivity wrote: > >> Anthony Liguori wrote: > >> > >>> This patch changes virtio devices to be multi-function devices whenever > >>> possible. This increases the number of virtio devices we can > >>> support now by > >>> a factor of 8. > >>> > >>> With this patch, I've been able to launch a guest with either 220 > >>> disks or 220 > >>> network adapters. > >>> > >>> > >> > >> Does this play well with hotplug? Perhaps we need to allocate a new > >> device on hotplug. > >> > > > > Probably not. I imagine you can only hotplug devices, not individual > > functions? > > > > It sounds reasonable to expect so. ACPI has objects for devices, not > functions (IIRC). So what I dislike about multifunction devices is the fact that a single slot shares an IRQ, and that special code is required in the QEMU drivers (virtio guest capability might not always be present). I don't see any need for using them if we can extend PCI slots... > Maybe require explicit device/function assignment on the command line? > It will be managed anyway. ACPI does support hotplugging of individual functions inside slots, not sure how well does Linux (and other OSes) support that.. should be transparent though. ------------------------------------------------------------------------- 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