From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37186) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YxGTH-0002FL-1S for qemu-devel@nongnu.org; Tue, 26 May 2015 11:08:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YxGTC-0001rg-Bc for qemu-devel@nongnu.org; Tue, 26 May 2015 11:08:46 -0400 Message-ID: <55648C66.5030208@redhat.com> Date: Tue, 26 May 2015 17:08:22 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1429964684-23872-1-git-send-email-aik@ozlabs.ru> <1429964684-23872-7-git-send-email-aik@ozlabs.ru> <55633A54.8080807@ozlabs.ru> <20150526024628.GA30620@voom.redhat.com> <5564359A.2070009@redhat.com> <556447BB.9000802@ozlabs.ru> <55644819.3000003@redhat.com> <55646803.8040007@ozlabs.ru> <55646C18.4000303@redhat.com> <5564750C.8000100@ozlabs.ru> <556475BD.50401@redhat.com> <55647843.4040609@ozlabs.ru> <556479B6.1010501@redhat.com> <55647C75.5000704@ozlabs.ru> <55647D4C.6060008@redhat.com> <55648086.3010804@ozlabs.ru> <55648239.7070905@redhat.com> <55648A7F.9070100@ozlabs.ru> In-Reply-To: <55648A7F.9070100@ozlabs.ru> Content-Type: text/plain; charset=koi8-r Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH qemu v7 06/14] spapr_iommu: Introduce "enabled" state for TCE table List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alexey Kardashevskiy , David Gibson Cc: Michael Roth , Alex Williamson , qemu-ppc@nongnu.org, qemu-devel@nongnu.org, Alexander Graf On 26/05/2015 17:00, Alexey Kardashevskiy wrote: >>>> Why do you need different regions? Why can't you have always the same >>>> IOMMU regions, and either: >>> >>> They may change a size. >> >> That's not a problem, there's memory_region_set_size for that. > > It was not there when I started doing this DDW :) If so, I can keep the > existing structure and just set size to zero instead of > memory_region_del_subregion(). del/add_subregion is okay. It's just init/unparent that is wrong. > I need windows appear and disappear on a bus dynamically, that's it. The > actual sPAPRTCETable objects exist always. Great. > Aliases will do the job as far as I can tell. Then you can choose between init_alias/add/del/unparent(alias) and del/set_size/add which Michael has mentioned. The latter is probably cleaner and faster. > sPAPRTCETable stores the actual table and if I want it to migrate, the > destination QEMU must have the object created-and-vmstate_register'ated. > But the table (and class) may be absent or present on the source side so > I need to start the destination with or without -device sPAPRTCETable, > and if I need to create this object, I need to make it a child of a PHB > and last time I checked - there is no command line interface for linking > children. Yup, understood now. > But I started thinking that always having 2 sPAPRTCETable objects (some > may be "disabled") it not better than a single sPAPRTCETable with > multiple TCE tables... Whatever works best for you. Either is okay. Paolo