From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 6/6] virtio ring helper Date: Sun, 23 Sep 2007 13:46:21 +0200 Message-ID: <46F6520D.5020103@qumranet.com> References: <1190289808.7262.223.camel@localhost.localdomain> <1190290140.7262.228.camel@localhost.localdomain> <1190290369.7262.231.camel@localhost.localdomain> <1190290495.7262.235.camel@localhost.localdomain> <1190290606.7262.239.camel@localhost.localdomain> <1190290761.7262.242.camel@localhost.localdomain> <1190291234.7262.246.camel@localhost.localdomain> <46F26AF6.60904@qumranet.com> <1190340251.19451.36.camel@localhost.localdomain> <46F63A64.9070200@qumranet.com> <1190547607.27805.120.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel , lguest , virtualization To: Rusty Russell Return-path: In-Reply-To: <1190547607.27805.120.camel-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Rusty Russell wrote: > On Sun, 2007-09-23 at 12:05 +0200, Avi Kivity wrote: > >> Rusty Russell wrote: >> >>> On Thu, 2007-09-20 at 14:43 +0200, Avi Kivity wrote: >>> >>>> 32 bits of page numbers give 44 bits of physical address on x86. That's >>>> 16TB per guest. Admittedly it's smaller on a VAX. >>>> >>> I like to feel that I make these mistakes to ensure others are paying >>> attention. However, it does mean that I can just put an address in >>> there and increase the length field to 32 bits. Much rejoicing. >>> >>> >> Why are we sending page numbers anyway? See below. >> > > Perhaps I was unclear. I already changed to a 64-bit address. I > haven't send out another set of patches because I'm changing to Arnd's > explicit virtio bus too. Will send out a new set tomorrow at this rate. > > It does say so quite explicitly in the quoted text. Sorry. >> Where one of the flags is VRING_DESC_INDIRECT, which means that the >> memory within (address, length) is a bunch of descriptors instead of raw >> data. >> > > If that's all we wanted, it's fairly easy to do as a future extension > even if we didn't change it today. My concern was the allocation and > management of those sg pages; hence my desire for a patch 8) > Won't kmalloc()/kfree() suffice? IMO the tradeoff (compared to chaining with its reduction in ring size, and handling ood) is positive. I'll try a patch based on the next patchset. -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/