From mboxrd@z Thu Jan 1 00:00:00 1970 From: Carsten Otte Subject: Re: [kvm-ppc-devel] RFC/patch portability: split kvm_vm_ioctl v2 Date: Fri, 26 Oct 2007 12:30:51 +0200 Message-ID: <4721C1DB.3040207@de.ibm.com> References: <1192192452.7630.16.camel@cotte.boeblingen.de.ibm.com> <1193327325.8345.9.camel@cotte.boeblingen.de.ibm.com> <1193327326.3284.2.camel@izike-woof.qumranet.com> <1193329322.28279.21.camel@basalt> <472114B6.6080000@qumranet.com> <1193345465.28279.47.camel@basalt> <4721A185.1070808@qumranet.com> <4721A3A3.8020504@de.ibm.com> <4721A82A.2040402@de.ibm.com> <4721B1ED.6040006@qumranet.com> Reply-To: carsteno-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-ppc-devel , carsteno-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org, Hollis Blanchard , carsteno-tA70FqPdS9bQT0dZR+AlfA@public.gmane.org, "kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org" , "Zhang, Xiantao" To: Avi Kivity Return-path: In-Reply-To: <4721B1ED.6040006-atKUWr5tajBWk0Htik3J/w@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 Avi Kivity wrote: > I don't really see a big difference between what we have now (sparse > userspace, sparse guest) and Izik's idea (contiguous userspace, sparse > guest). In both cases you need something like memory slots to describe > the different sections. We don't on s390: we receive a page fault by the guest once it accesses a sparse hole in its address space. We check the user space's VMA and either page it in or submit an addressing exception to the guest. > Moreover, on x86 you may want different properties for different > sections (4K pages for the framebuffer, large pages for main memory), so > you can't allocate memory in one big chunk. That's right. On s390, we can live with whatever properties a section has with regard to page size, backing device and such. So memory may well come to live by different alloations, and different allocation methods. All we need is a permanent contiguous mapping of the guest physical addresses to host user addresses. So Izik's idea would work for us even if we have different sections. ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/